how can i add '\0' at the end of a string which is referred to using a pointer?

Question

I want to check if string b is suffix of string a. I have tried this so far:

    char a[20], b[20];
    char *p;
    gets(a);
    gets(b);

    p = strstr(a,b);
    while(p != NULL)
    {
        if(p + strlen(b) == '\0')
            break;
        p = strstr(p+1, b);
    }

I have opened the debugger and have seen that when the program reaches this line:

if(p + strlen(b) == '\0')

It never validates to true because p + strlen(b) isn't \0 but just \.

How can I add \0 at the end of what p is pointing to?

Mad Physicist · Accepted Answer · 2014-02-08 04:56:56Z

1

You need to derfernce the pointer that you are computing:

Either

if(*(p + strlen(b)) == '\0')

or

if(p[strlen(b)] == '\0')

should do it.

edited Feb 8, 2014 at 4:56

answered Feb 7, 2014 at 21:50

Mad Physicist

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2 Comments

user3285580 Over a year ago

Which library should I use for strrstr? Cstring or String.h doesn't seem to work for me.

Mad Physicist Over a year ago

You are right. It is a non-standard function available on linux via sstrings2.h, and possibly having to link using -lsstrings2: linux.die.net/man/3/strrstr. I have removed it from my answer because of this.

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