How do I print a char pointer returned by a function (C)?

Asked Jun 20 '19 at 15:41

Active Jun 20 '19 at 15:43

Viewed 33 times

I am trying to print a char pointer returned by a function but the output is always gibberish.

I have tried changing the function type to char [] but this gives error. I have also tried casting the char [] to char * but this causes stack corruption. I noticed that if variable 'b' is printed within the function before the return statement, it displays correctly.

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

char *the()
{
    char a[100] = "Ace of Spades";
    char * b = &a[0];

    return b;
}
int main(void)
{

        printf("%s\n", the());

}

Expected Result: Actual Result:

edited Jun 20 '19 at 15:43

asked Jun 20 '19 at 15:41

jacobay43

2

you access to a local variable whose does not exist anymore, the behavior is undefined, copy / duplicate the string before to return it or move _a_ static – bruno Jun 20 '19 at 15:43
`char*` and `char[]` are the same thing – gogaz Jun 20 '19 at 15:43
@bruno I don't understand your correction, copy the string to where? – jacobay43 Jun 20 '19 at 15:44
@gogaz You can't declare a function as char [] (), I've tried it with VS 2013 – jacobay43 Jun 20 '19 at 15:45
This is pretty much an exact duplicate question. The `char a[100]` ceases to exist when the function containing it returns. – Andrew Henle Jun 20 '19 at 15:45
1

@gogaz not exactly but `char[]` decays to a pointer here. – Yastanub Jun 20 '19 at 15:46
@jacobay43 you can duplicate it (strdup), do not forget to free it later in _main_ in that case – bruno Jun 20 '19 at 15:46
@bruno When I duplicate it, how can the duplicate be returned? – jacobay43 Jun 20 '19 at 15:47
1

@jacobay43 replace `return b;` by `return strdup(b);` then in _main_ replace `printf("%s\n", the());` by `char * s = the(); puts(s); free(s);` (_puts_ more practical than _printf_ in your case) – bruno Jun 20 '19 at 15:47
1

@bruno, it works now, thanks – jacobay43 Jun 20 '19 at 15:51

How do I print a char pointer returned by a function (C)?

0 Answers0