strcmp

                                    #include<stdio.h> 
#include<string.h> 


int main() 
{  
      
    char char1[] = "coucou"; 
    char char2[] = "coucou"; 
      
  	if( strcmp(char1, char2) == 0 )
       printf("Strings are the same");
  
  	else
      prinf("Strings are differentes");
  
  
    return 0; 
}

                                    #include <string.h>

                                    return
	>0 if first string is large
    <0 if first string is short
     0 if strings are equal
    
int strcmp ( const char * str1, const char * str2 );

                                    STRCMP (const char *p1, const char *p2)
{
  const unsigned char *s1 = (const unsigned char *) p1;
  const unsigned char *s2 = (const unsigned char *) p2;
  unsigned char c1, c2;
  do
    {
      c1 = (unsigned char) *s1++;
      c2 = (unsigned char) *s2++;
      if (c1 == '\0')
        return c1 - c2;
    }
  while (c1 == c2);
  return c1 - c2;
}