If statement
If statement example to validate voter’s age (one way branching)
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 3-Oct-2022, 8.00 pm
void main()
{
int age=15;
clrscr();
printf ("enter your age : ");
scanf ("%d",&age);
// printf ("start\n");
if (age>=18)
//if (age<0)
{
printf ("you can vote\n");
printf ("please vote !");
}
// printf ("end");
getch();
}If else statement to validate voter’s age (two way branching)
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 3-Oct-2022, 8.00 pm
# include <stdio.h>
void main()
{
int age;
clrscr();
printf ("enter your age : ");
scanf ("%d",&age);
if (age>=18)
{
printf ("you can vote\n");
printf ("please vote !");
}
else
{
printf ("\nsorry ! you can not vote\n");
printf ("\n\nplease do wait for %d year(s)",18-age);
}
getch();
}Calculate bill amount with discount, when bill amount is greater than 2000
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 3-Oct-2022, 8.00 pm
# include <stdio.h>
void main()
{
float bamt,disc=0,fbamt;;
clrscr();
printf ("Enter bill amount : ");
scanf ("%f",&bamt);
if (bamt>=2000)
{
disc = (bamt * 5)/100;
}
fbamt = bamt - disc;
printf ("\nBill amount : %f",bamt);
printf ("\nDiscount amount : %f",disc);
printf ("\nFinal bill amount : %f",fbamt);
getch();
}if else if statement to check vowels from given character
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 3-Oct-2022, 8.00 pm
# include <stdio.h>
void main()
{
char c;
clrscr();
printf ("enter a character : ");
scanf ("%c",&c);
if (c == 'a')
{
printf ("a is vowel");
}
else if (c == 'e')
{
printf ("e is vowel");
}
else if (c == 'i')
{
printf ("i is vowel");
}
else if (c == 'o')
{
printf ("o is vowel");
}
else if (c == 'u')
{
printf ("u is vowel");
}
else
{
printf ("char is consonent");
}
getch();
}Switch statement
Program to print day name when user enters a day number from week
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 3-Oct-2021, 8.00 pm
# include <stdio.h>
void main()
{
int day;
clrscr();
printf ("enter day number : ");
scanf ("%d",&day);
switch (day)
{
case 1:
printf ("today is monday");
break;
case 2:
printf ("today is tuesday");
break;
case 3:
printf ("today is wednesday");
break;
case 4:
printf ("today is thursday");
break;
case 5:
printf ("today is friday");
break;
case 6:
printf ("today is saturday");
break;
case 7:
printf ("today is sunday");
break;
default:
printf ("invalid day number");
break;
}
getch();
}Program to check vowel from a given character
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 3-Oct-2021, 8.00 pm
void main()
{
char c;
clrscr();
printf ("enter a character : ");
//scanf ("%c",&c);
c = getchar();
switch (c)
{
case 'a':
case 'e':
case 'i':
case 'o':
case 'u':
case 'A':
case 'E':
case 'I':
case 'O':
case 'U':
printf ("char is vowel");
break;
default:
printf ("char is consonant");
break;
}
getch();
}Program to perform arithmetic operation on two number, operation is given as an input, switch case use to identify operation.
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 3-Oct-2021, 8.00 pm
void main()
{
int a,b;
char c;
clrscr();
printf ("enter number 1 : ");
scanf ("%d",&a);
printf ("enter number 2 : ");
scanf ("%d",&b);
printf ("enter a operation (+ - * /) : ");
flushall();
c = getchar();
switch (c)
{
case '+':
printf ("addition = %d",a+b);
break;
case '-':
printf ("subtraction = %d",a-b);
break;
case '*':
printf ("multiplication = %d",a*b);
break;
case '/':
printf ("division = %d",a/b);
break;
default:
printf ("invalid operation");
break;
}
getch();
}Array
Initialize an Array in C
void main()
{
// Size of the array is taken as the number of elements
// in the initializer list (5)
int arr[] = {1, 2, 3, 4, 5};
// here, size of a is 3
int a[] = {1, 2, 3};
// char array
char n[] = {'r','a','\0'};
// initialize the two dimensional array.
int arr[3][3] = {1,2,3, 4,5,6, 7,8,9};
}One dimensional array example
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 25-Nov-2021, 12.00 pm
void main()
{
int marks[10];
int i,n;
clrscr();
printf ("Enter Size : ");
scanf ("%d",&n);
for (i=0; i<n; i++)
{
printf ("enter [%d] element : ",i+1);
scanf ("%d",&marks[i]);
}
printf ("\nStored Values in Array \n");
for (i=0; i<n; i++)
{
printf ("[%d] ",marks[i]);
}
getch();
}
Output :
Enter Size : 4
enter [1] element : 23
enter [2] element : 90
enter [3] element : 87
enter [4] element : 56
Stored Values in Array
[23] [90] [87] [56]Example to calculate sum and average of array elements. To find minimum and maximum value from array element with index number.
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 3-Oct-2021, 8.00 pm
void main()
{
int mark[5],i,n;
int s=0, avg=0;
int min,max;
int minp,maxp;
clrscr();
printf ("\n\nenter array size : : ");
scanf ("%d",&n);
for(i=0; i<n; i++)
{
printf ("enter %d element : ",i+1);
scanf ("%d",&mark[i]);
}
min=mark[0];
max=mark[0];
minp=0;
maxp=0;
for(i=0; i<n; i++)
{
if(mark[i]>max)
{
max=mark[i];
maxp=i;
}
if(mark[i]<min)
{
min=mark[i];
minp=i;
}
s=s+mark[i];
printf ("[%d] -> %d\n",i+1, mark[i]);
}
avg=s/n;
printf ("\n\n Sum = %d",s);
printf ("\n\n Avg = %d",avg);
printf ("\n\n [%d] -> Min = %d",minp+1, min);
printf ("\n\n [%d] -> Max = %d",maxp+1, max);
getch();
}Example of two dimensional array
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 25-Nov-2021, 12.00 pm
void main()
{
int marks[10][10];
int r,c,i,j,n;
printf ("Enter Row Size : ");
scanf ("%d",&r);
printf ("Enter Column Size : ");
scanf ("%d",&c);
for (i=0; i<r; i++)
{
for (j=0; j<c; j++)
{
printf ("enter [%d][%d] element : ",i+1,j+1);
scanf ("%d",&marks[i][j]);
}
}
printf ("\nStored Values in Mark Array \n");
for (i=0; i<r; i++)
{
for (j=0; j<c; j++)
{
printf ("[%d] ",marks[i][j]);
}
printf ("\n");
}
getch();
}
Output:
Enter Row Size : 2
Enter Column Size : 4
enter [1][1] element : 45
enter [1][2] element : 67
enter [1][3] element : 89
enter [1][4] element : 43
enter [2][1] element : 66
enter [2][2] element : 99
enter [2][3] element : 33
enter [2][4] element : 12
Stored Values in Mark Array
[45] [67] [89] [43]
[66] [99] [33] [12]Example of multi dimensional array
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 29-Nov-2021, 7.00 pm
void main()
{
// declare 2-array of 2-rows and 2-columns total 2x2x2=8 elements
int a[2] [2][2];
a[0] [0] [0] = 1;
a[0] [0] [1] = 2;
a[0] [1] [0] = 3;
a[0] [1] [1] = 4;
a[1] [0] [0] = 5;
a[1] [0] [1] = 6;
a[1] [1] [0] = 7;
a[1] [1] [1] = 8;
printf ("0th array from multi-dimensional array \n");
printf ("%d ", a[0] [0] [0]);
printf ("%d ", a[0] [0] [1]);
printf ("%d ", a[0] [1] [0]);
printf ("%d ", a[0] [1] [1]);
printf ("\n\n1st array multi-dimensional array \n");
printf ("%d ", a[1] [0] [0]);
printf ("%d ", a[1] [0] [1]);
printf ("%d ", a[1] [1] [0]);
printf ("%d ", a[1] [1] [1]);
getch();
}
Output:
0th array from multi-dimensional array
1 2 3 4
1st array multi-dimensional array
5 6 7 8Char array example
void main()
{
int i,n;
// char array with 20 chars (size)
char name[20];
// or
// char *name; // dynamic size, its size will be determine by the number of chars set in array
clrscr();
printf ("\n\nenter your name : ");
scanf ("%s",name);
printf ("%s\n\n",name);
n=strlen(name);
printf ("\nchar array in ascending order \n");
for(i=0; i<n; i++)
{
printf ("%c",name[i]);
}
printf ("\nchar array in reverse order\n");
for(i=n-1; i>=0; i--)
{
printf ("%c",name[i]);
}
getch();
}Example of two dimension array of string
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 03-Dec-2021, Friday
void main()
{
char cities[10][20];
int i,n;
printf("Enter the no. of cities (max.< 10): ");
scanf("%d",&n);
for(i=0; i<n; i++)
{
printf("Enter %d city name :",i+1);
scanf("%s",cities[i]);
}
printf("\nEntered city names are:\n");
for(i=0; i<n; i++)
{
//puts(cities[i]);
printf ("%s (%d)",cities[i],strlen(cities[i]));
}
getch();
}Example to find and replace a character in two dimensional string
# include <stdio.h>
# include <conio.h>
# include <string.h>
// www.raviroza.com
// 03-Dec-2021, Friday
void main()
{
char cities[10][20];
char find,repl;
int i,n,k, len, cnt=0;
printf("Enter the no. of cities (max.< 10): ");
scanf("%d",&n);
for(i=0; i<n; i++)
{
printf("Enter %d city name :",i+1);
scanf("%s",cities[i]);
}
flushall();
printf ("Enter char to find : ");
scanf ("%c",&find);
flushall();
printf ("Enter char to replace with : ");
scanf ("%c",&repl);
printf("\nEntered city names are:\n");
for(i=0; i<n; i++)
{
len = strlen(cities[i]);
for (k=0; k<len; k++)
{
if(cities[i][k] == find)
{
// replace the found character
cities[i][k] = repl;
// to count the no. of replacement
cnt++;
}
printf ("%c",cities[i][k]);
}
printf ("\n");
}
printf ("'%c' found & replaced %d times ",find,cnt);
getch();
}
Output:
Enter the no. of cities (max.< 10): 3
Enter 1 city name : Jamnagar
Enter 2 city name : Rajkut
Enter 3 city name : Baroda
Enter char to find : r
Enter char to replace with : @
Entered city names are :
Jamnaga@
Rajkot
Ba@oda
‘r’ found & replaced '2' timesUser Defined Functions
FUNCTION WITH NO ARGUMENTS AND NO RETURN VALUE
When a function has no arguments and it does not return a value to the caller, when there is no data transfer between calling function and called function.
// function declaration
void f1();
void f1()
{
printf ("function f1 is called");
}
void main()
{
// here main is the calling function
f1();
// f1() is the called function
}FUNCTION WITH ARGUMENTS AND NO RETURN VALUE
When a function has argument(s), but does not return a value to the caller, data is passed to the called function and no data is returned to the calling function
// function declaration
void f1(int);
void f1(int i)
{
printf ("function f1 is called with data/argument(s) -> %d",i);
}
void main()
{
// here main is calling function
// function f1() is called with a data (arguments)
f1(10);
// f1() is the called function
}FUNCTION WITH NO ARGUMENTS AND RETURN VALUE
When a function has no argument, but it does return a value to the caller, no data is passed to the called function but data is returned to the calling function.
// function declaration
int f1();
void f1()
{
int a = 10;
int b = 10;
int c = a + b;
return c;
}
void main()
{
// here main is calling function
// function f1() is called with no data (arguments)
int t = f1();
printf ("returned value = %d",t);
// or
printf ("returned value = %d",f1());
}FUNCTION WITH ARGUMENTS AND RETURN VALUE
When a function has argument(s), and it also does return a value to the caller, data is passed to the called function and data is also returned to the calling function.
// function declaration
int f1(int , int );
void f1(int n1, int n2)
{
int c = n1 + n2;
return c;
}
void main()
{
// here main is calling function
// function f1() is called with no data (arguments)
int t = f1(100,200);
printf ("returned value = %d",t);
// or
printf ("returned value = %d",f1(100,200));
}UDF to print Static/Fix line, line with N columns and line with N columns and C character/symbol.
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 7-Dec-2021, 11.00 pm
// function prototype
//-------------------
void line1();
void line2(int);
void line3(int,char);
//-------------------
// function definitions
// function to print line with fix columns
void line1()
{
printf ("\n--------------------\n");
}
// function to print line with n number of columns
void line2(int n)
{
int i;
printf ("\n");
for(i=1; i<=n; i++)
{
printf ("-");
}
printf ("\n");
}
// function to print line with n number of columns & given symbol/char
void line3(int n, char c)
{
int i;
printf ("\n");
for(i=1; i<=n; i++)
{
printf ("%c",c);
}
printf ("\n");
}
int main()
{
// to print line with fix columns
line1();
// to print line with n columns
line2(5);
// to print line with n columns & given symbol/char
line3 (10,'@');
getch();
}
CALL BY VALUE
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 8-Dec-2021, 10.30 am
void byval(int);
void byval(int i)
{
i=i+1;
}
void main()
{
int temp=10;
byval(temp);
printf ("temp = %d",temp);
getch();
}CALL BY REFERENCE
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 8-Dec-2021, 10.30 am
void byref(int*);
void byref(int *i)
{
*i = *i + 1;
}
void main()
{
int temp=10;
byref(&temp);
printf ("\n\ntemp = %d",temp);
getch();
}ARRAY (int, char) AS PARAMETER TO FUNCTION
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 28-Dec-2021, 7.57 am
void fun(int array[], int size)
{
int i;
for(i=0; i<size; i++)
printf ("%d\n",array[i]);
}
void fun1(char array[])
{
int i;
for(i=0; i<strlen(array); i++)
printf ("%c",array[i]);
}
void main()
{
int arr[] = {1,2,3,4,5,6,7,8,9,10};
char *c = "ravi r oza";
clrscr();
fun(arr,10);
fun1(c);
getch();
}Structure
STRUCTURE EXAMPLE
# include <stdio.h>
# include <conio.h>
// author : www.raviroza.com
// date : 8-Dec-2021, 8.00 am
struct Student
{
int no;
char name[20];
float perc;
};
void main()
{
struct Student s1;
fflush(stdin);
printf ("enter Student number : ");
scanf ("%d",&s1.no);
fflush(stdin);
printf ("enter Student Name : ");
scanf ("%s",s1.name);
fflush(stdin);
printf ("enter Student percentage : ");
scanf ("%f",&s1.perc);
printf ("\nStudent Summary\n\n");
printf ("No. : %d\n",s1.no);
printf ("Name : %s\n",s1.name);
printf ("Percentage : %f\n",s1.perc);
getch();
}
ARRAY OF STRUCTURE EXAMPLE
# include <stdio.h>
# include <conio.h>
// author : www.raviroza.com
// date : 8-Dec-2021, 9.45 am
struct Student
{
int no;
char name[20];
float perc;
};
void main()
{
struct Student stu[5];
int i, n;
printf ("enter no. of student : ");
scanf ("%d",&n);
for (i=0; i<n; i++)
{
fflush(stdin);
printf ("enter Student number : ");
scanf ("%d",&stu[i].no);
fflush(stdin);
printf ("enter Student Name : ");
scanf ("%s",stu[i].name);
fflush(stdin);
printf ("enter Student percentage : ");
scanf ("%f",&stu[i].perc);
}
printf ("\nStudent Summary\n");
printf ("\n----------------------------\n");
for (i=0; i<n; i++)
{
printf ("No. : %d\n",stu[i].no);
printf ("Name : %s\n",stu[i].name);
printf ("Percentage : %f\n",stu[i].perc);
printf ("\n----------------------------\n");
}
getch();
}
POINTER TO STRUCTURE EXAMPLE
# include <stdio.h>
# include <conio.h>
// author : www.raviroza.com
// date : 20-Dec-2021, 8.00 am
struct Student
{
int no;
char name[20];
};
void main()
{
struct Student *sptr, stu1;
sptr = &stu1;
printf("Enter Student No. : ");
scanf("%d", &sptr->no);
printf("Enter Student Name : ");
scanf("%s", &sptr->name);
printf("Student Details:\n");
printf("No. : %d\n", sptr->no);
printf("Name : %s", sptr->name);
getch();
}STRUCTURE WITHIN STRUCTURE
# include <stdio.h>
# include <conio.h>
// author : www.raviroza.com
// date : 20-Dec-2021, 8.30 am
struct student
{
int no;
char *name;
struct marks
{
int m1,m2,m3;
}mark;
};
// typedef is used to create the alias of data types
typedef struct student stu;
void main()
{
//struct student s;
stu s;
s.no=101;
s.name = "ravi r oza";
s.mark.m1=75;
printf ("%d %s %d",s.no,s.name,s.mark.m1);
getch();
}Pointers
Pointer for int, float and char.
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 11-Dec-2021, 8.00 am
void main()
{
printf("\n Pointer Demo \n");
int i = 10;
int *iptr;
float f = 10.34;
float *fptr;
char c = 'r';
char *cptr;
iptr = &i;
fptr = &f;
cptr = &c;
printf ("int : %d is at %p\n",i,iptr);
printf ("float : %f is at %p\n",f,fptr);
printf ("char : %c is at %p\n",c,cptr);
getch();
}Address of Array elements
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 11-Dec-2021, 9.00 am
int main()
{
int arr[5];
int i;
printf ("\n\n POINTERS/ADDRESS OF ARRAY ELEMENTS \n");
for(i = 0; i < 5; ++i)
{
printf("&arr[%d] = %p\n", i, &arr[i]);
}
printf("Base Address of Array is : %p", arr);
getch();
}Pointer to an Array
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 11-Dec-2021, 9.00 am
int main()
{
int arr[5] = {1, 2, 3, 4, 5};
int* ptr;
// ptr is assigned the address of the 1st element
ptr = &arr[0];
printf("*ptr : %d\n", *ptr); // 1
printf("*(ptr+1) : %d\n", *(ptr+1)); // 2
printf("*(ptr+2) : %d", *(ptr+2)); // 3
getch();
}Pointer to Structure
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 7-Oct-2022, 8.25 am
struct student
{
int age;
float weight;
};
void main()
{
struct student *studentPtr, student1;
studentPtr = &student1;
clrscr();
printf("Enter age : ");
scanf("%d", &studentPtr->age);
printf("Enter weight : ");
scanf("%f", &studentPtr->weight);
printf("Displaying Student Details:\n");
printf("Age: %d\n", studentPtr->age);
printf("weight: %f", studentPtr->weight);
getch();
}Pointer to Pointer
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 11-Oct-2022, 4.8 pm
void main()
{
// integer memory variable
int x=10;
// pointer, referencing to integer x
int *p;
// *p, pointer to pointer, referencing to pointer p
int **ptp;
p = &x;
ptp = &p;
// changing the value of x using pointer to pointer variable
**ptp = **ptp + 1;
printf ("x = %d ",**ptp);
getch();
}Pointer as an argument to a function (function call by reference)
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 8-Dec-2021, 10.30 am
void byref(int*);
void byref(int *i)
{
*i = *i + 1;
}
void main()
{
int temp=10;
byref(&temp);
printf ("\n\ntemp = %d",temp);
getch();
}Storage classes
Automatic example
void main()
{
int n;
}
// the above code can also be written as
void main()
{
auto int n;
// it has the same meaning as above example
}External example
extern int i = 99;
//above is accessed from multiple files.
or
int i = 99;
// above is restricted to current program.
void fun1()
{
i = 1;
}
void fun2()
{
i = i + 1;
}
void main()
{
printf ("%d",i);
f1();
printf ("%d",i);
f2();
printf ("%d",i);
}Static example
void fun1()
{
static int i=1;
}
void main()
{
fun1();
fun1();
}Register example
void main()
{
register int i;
for (i=1; i<=5; i++)
{
printf ("it is printed faster using register variables\n");
}
}File Handling
Write data to file (Single Character )
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 07-Jan-2022, 6.07 pm
void main()
{
char c;
FILE *fp;
printf ("Enter char to write in file : ");
scanf ("%c",&c);
fp = fopen("f1.txt","w");
putc(c,fp);
fclose(fp);
printf ("a character is written in file");
getch();
}Read data from File (single character)
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 09-Jan-2022, 4.05 pm
// read single (probably first) character from file
void main()
{
char c;
FILE *fp;
fp = fopen("f1.txt","r");
c = getc(fp);
printf ("%c",c);
getch();
fclose(fp);
}Read complete data using getc() from File
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 09-Jan-2022, 4.15 pm
// read full file, using while loop and EOF (end of file)
void main()
{
char c;
FILE *fp;
fp = fopen("f1.txt","r");
while((c = getc(fp)) != EOF)
{
printf ("%c",c);
}
fclose(fp);
getch();
}Read and Write int data
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 09-Jan-2022, 4.45 pm
void main()
{
int age;
FILE *fp;
fp = fopen("fint.txt","w");
printf ("WRITE integer data from file\n");
printf ("Enter age : ");
scanf ("%d",&age);
putw(age,fp);
printf ("Enter age1 : ");
scanf ("%d",&age);
putw(age,fp);
fclose(fp);
printf ("READ integer data from file\n");
fp = fopen("fint.txt","r");
while((age = getw(fp)) != EOF)
{
printf ("%d",age);
}
fclose(fp);
getch();
}fprintf() and fscanf() example
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 10-Jan-2022, 4.54 pm
void main()
{
int age,c;
char name[10];
FILE *fp;
fp = fopen("fmixdata.txt","w");
printf ("WRITE Mix-Data to File\n");
printf ("Enter Name : "); scanf ("%s",name);
printf ("Enter age : "); scanf ("%d",&age);
fprintf(fp,"%10s%3d",name,age);
fclose(fp);
printf ("READ Mix-Data from file\n");
fp = fopen("fmixdata.txt","r");
while((fscanf(fp,"%10s%3d",name,&age)) != EOF)
{
printf ("Name -> %s\n",name);
printf ("Age -> %d\n",age);
}
fclose(fp);
getch();
}Misc.
Program to find ASCII value of given character
# include <stdio.h>
# include <conio.h>
// www.raviroza.com
// 3-Oct-2022, 8.00 pm
void main()
{
char a;
//int b=98;
clrscr();
printf ("enter a character : ");
scanf ("%c",&a);
printf ("ASCII value of %c is -> %d ",a);
getch();
}