What is strcmp() Function in C language?

The C library function int strcmp(const char *str1, const char *str2) compares the string pointed to, by str1 to the string pointed to by str2.

An array of characters is called a string.

Declaration

Following is the declaration for an array −

char stringname [size];

For example − char string[50]; string of length 50 characters

Initialization

• Using single character constant −

char string[10] = { ‘H’, ‘e’, ‘l’, ‘l’, ‘o’ ,‘\0’}

• Using string constants −

char string[10] = "Hello":;

Accessing − There is a control string "%s" used for accessing the string till it encounters ‘\0’.

The strcmp() function

• This function compares two strings.

• It returns the ASCII difference of the first two non – matching characters in both the strings.

String comparison

The syntax is as follows −

int strcmp (string1, string2);

If the difference is equal to zero ------ string1 = string2

If the difference is positive ------- string1> string2

If the difference is negative ------- string1 <string2

Example Program

The following program shows the usage of strcmp() function −

#include<stdio.h>
main ( ){
   char a[50], b [50];
   int d;
   printf ("enter 2 strings:\n");
   scanf ("%s %s", a,b);
   d = strcmp (a,b);
   if (d==0)
      printf("%s is equal to %s", a,b);
   else if (d>0)
      printf("%s is greater than %s",a,b);
   else if (d<0)
      printf("%s is less than %s", a,b);
}

Output

When the above program is executed, it produces the following result −

enter 2 strings:
bhanu
priya
bhanu is less than priya

Let’s see another example on strcmp().

Given below is the C program to compare two strings using strcmp library function −

Example

#include<stdio.h>
#include<string.h>
void main(){
   //Declaring two strings//
   char string1[25],string2[25];
   int value;
   //Reading string 1 and String 2//
   printf("Enter String 1: ");
   gets(string1);
   printf("Enter String 2: ");
   gets(string2);
   //Comparing using library function//
   value = strcmp(string1,string2);
   //If conditions//
   if(value==0){
      printf("%s is same as %s",string1,string2);
   }
   else if(value>0){
      printf("%s is greater than %s",string1,string2);
   }
   else{
      printf("%s is less than %s",string1,string2);
   }
}

Output

When the above program is executed, it produces the following result −

Enter String 1: Tutorials
Enter String 2: Point
Tutorials is greater than Point