C Library - strncmp() function

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The C library strncmp() function is used to compare at most a specified number of characters from two null-terminated strings. This string is also known as end of the string i.e. defined through the occurrence of a null character.

Syntax

Following is the syntax of the C library strncmp() function −

 strncmp(const char *str1, const char *str2, size_t n) 

Parameters

This function accepts the following parameters −

• str1 − This is the first string to be compared.

• str2 − This is the second string to be compared.

• n − This parameter refer to maximum number of characters to be compared.

Return Value

This function returns integer value which is −

• Negative, if the str1 is less than str2.

• Positive, if the str2 is less than str1.

• zero, if the str1 is equal to str2.

Example 1

Following is the C library strncmp() function that checks whether the given two strings are equal or not.

 #include <stdio.h> #include <string.h> int main() { char str_1[] = "java"; char str_2[] = "java"; if (strncmp(str_1, str_2, strlen(str_2)) == 0) { printf("The strings '%s' and '%s' are equal.\n", str_1, str_2); } else { printf("The strings '%s' and '%s' are not equal.\n", str_1, str_2); } return 0; } 

Output

On execution of above code, we get the following result −

 The strings 'java' and 'java' are equal. 

Example 2

Below the mentioned program state the two functions of C − strcpy() which create the string copy and using strncmp(), it compares the string.

 #include <stdio.h> #include <string.h> int main () { char str1[15]; char str2[15]; int ret; strcpy(str1, "abcdef"); strcpy(str2, "abcdEF"); ret = strncmp(str1, str2, 4); if(ret < 0) { printf("str1 is less than str2"); } else if(ret > 0) { printf("str2 is less than str1"); } else { printf("str1 is equal to str2"); } return(0); } 

Output

The above code produces the following output −

 str1 is equal to str2