In C program, how do I check if the input string is a specific name or not?

Question

#include<stdio.h>

int main(){

char name[20];

scanf(" %s", name);

if (name == 'James'){

    printf("Welcome James");
}else{

    printf("You are not James");
}

}

Hope you got my idea. I know this doesn't work. But is there any way to do something like this?

Better hope their name isn't "Alessandro de Alexandria" or you're going to blow that dinky character buffer. — tadman, Nov 07 '17 at 05:59

score 3 · Accepted Answer · answered Nov 07 '17 at 05:54

3

Use

if (strcmp(name, "James") == 0)

instead of

if (name == 'James')

Man page of strcmp:

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.

answered Nov 07 '17 at 05:54

msc

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It's worth noting that `==` compares string pointers, not strings, so it compiles but is generally not what people want. – tadman Nov 07 '17 at 05:57

Alden Ken · Answer 2 · 2017-11-07T06:13:25.210

2

try: strcmp()

#include<stdio.h>

int main(){

char name[20];

scanf(" %s", name);

if (strcmp(name,"James")){

    printf("Welcome James");
}else{

    printf("You are not James");
}

}

Ref : How do I properly compare strings?

edited Nov 07 '17 at 06:13

answered Nov 07 '17 at 05:56

Alden Ken

142
8

`strcmp(name,'James')` you sure about that? – Ajay Brahmakshatriya Nov 07 '17 at 06:11
@AjayBrahmakshatriya Opps, sorry syntax error. – Alden Ken Nov 07 '17 at 06:14

score 0 · Answer 3 · answered Nov 07 '17 at 06:06

In C you have to use cmp string function:

strcmp(const char* s1, const char* s2);

Return values of function:

return value == 0 - s1 is equals s2
return value > 0 - s1 is longer than s2
return value < 0- s1 is smaller than s2

It is beacuse if you write:

char name_buff[20];
if (name_buff == "James")
{
...

It doesn't mean comparsion of strings but of address in memory. So you have to use strcmp().

In C program, how do I check if the input string is a specific name or not?

3 Answers3