What is the issue with this reverse array code in c++?

Question

The program compile fine, but crashes when is running and shows this : Process terminated with status -1073741819

void reverse(char *str){

    char * end1 = str;
    char tmp = 'c';
    if(str){
        while(*end1){
            ++end1;
        }
        --end1;

        while(str<end1){
            tmp=*str;
            *str=*end1;
            *end1=tmp;
            str++;
            end1--;
        }
    }
}

Any idea ?

How are you calling reverse? Are you sure that the string you're passing is modifiable? I.e. not char* str = "foo";. — flogram_dev
– flogram_dev, Commented Mar 17, 2015 at 3:26
Yeah this function looks fine as is. You are likely calling it on illegal input. — jschultz410
– jschultz410, Commented Mar 17, 2015 at 3:28
not sure but have you used using namespace std; ? This might have collission with std::endl and char* endl — Jagannath
– Jagannath, Commented Mar 17, 2015 at 3:29
@Jagannath Nah, his is end1 not endl and even if it was, it would mask it due to being a locally declared variable. — jschultz410
– jschultz410, Commented Mar 17, 2015 at 3:30

Sergey Kalinichenko · Accepted Answer · 2015-03-17 03:30:30Z

2

There is absolutely nothing wrong with your reverse implementation: your code will work as long as the string that you pass is null-terminated and writable.

Then there must be something wrong with the way that you invoke it. The most common possibility is passing a string literal, writing to which is undefined behavior that may cause a crash:

char *s = "quick brown fox";
reverse(s); // <<== This would be undefined behavior

Demo of your working code.

answered Mar 17, 2015 at 3:30

Sergey Kalinichenko

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1 Comment

Gabriel Torres Over a year ago

Thanks , i wasn't paying attention to the way i called the function.

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