Comparing strings using strncmp() function in C language?

[Iron Hide]

Hello everyone,

I was working on a program which accepts 2 strings from the keyboard and the compared n characters from both strings. If n characters from each string equals then print out message saying that else print message saying otherwise. I know that I can use strncmp() function here, and also I need a loop to make a decision. It sounds simple but for some reason I cant make it work. Here is my code:

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

int main()
{
	char string1[20], string2[20];
	int n, result = 0;

	printf("\nEnter String 1:");
		gets(string1);
	printf("\nEnter String 2:");
		gets(string2);
	printf("\nEnter the n:");
		scanf("%d", &n);

	int result = strncmp(string1,string2,n);  // strncmp() function
	     if (result > 0)  // I am not sure what I am doing there
		  printf("\nMatch");
	     else
		  printf("\nNot a Match");

Please help me with this code
Thank you

[anduril462]

Don't use gets! You've been warned about this before. Fix your dirty, nasty habit, or else I refuse to help you. If you haven't yet, read why gets is bad and how to fix it here (that red text is a link -- click it).

[Iron Hide]

wow .. you need to calm down sir. Sry about that, and I just upgraded my code.

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

int main()
{
	char string1[20], string2[20];
	int n, result = 0;

	printf("\nEnter String 1:");
		scanf("%s",string1);
	printf("\nEnter String 2:");
		scanf("%s",string2);
	printf("\nEnter the n:");
		scanf("%d", &n);

	int result = strncmp(string1,string2,n);  // strncmp() function
	     if (result > 0)  // I am not sure what I am doing there
		  printf("\nMatch");
	     else
		  printf("\nNot a Match");

[anduril462]

I will be as calm or uncalm as I please, thank you very much. And since the gentle suggestions in the past didn't seem to work, I thought I would step it up a notch. Besides, it's for your own good -- consider it a little tough love.

scanf is okay for some things, but it will only read up to the first white space character, so you only get one word. That may be fine for what you need, but I'm guessing not in this case. The better solution would be:

fgets(string1, sizeof(string1), stdin);

Now, you should really, really read the docs for strncmp more carefully. If you're on Linux, "man strcmp" will work, or you can check your compiler help files and there's always Google:

RETURN VALUE
The strcmp() and strncmp() functions return an integer less than, equal to, or greater than zero if s1 (or the first n bytes thereof) is found, respectively, to be less
than, to match, or be greater than s2.

You only want to report a match if strncmp returns 0. Go ahead and change that to "if (result == 0)" and you should get better results.

[Iron Hide]

ah thanks it works and I love u too lol

jk