Question

Let me make this clear right away, this is for a college class. I cannot use C++ libraries, only standard C libraries. Do not suggest that I use C++ strings or cin/cout because that will not help me for this assignment.

My issue: I have global character arrays in the main function. I need to pass strings to the global character arrays from scanf() in a function foo(). Everything compiles fine, the issue is, the scanf() function seems to have no affect on the global character arrays that it points to. I’m using the “address of” operator (&) as the reference books indicate to do. Perhaps, I’m not understanding the relationship between the character array pointer and the scanf() “address of” (&). I feel I’ve looked everywhere for a solution.

I’ve spent several hours on this issue so I’m now looking for expert advice.

Here is a simplified version of my program.

#include <stdio.h>

void foo(char arr1[], char arr2[]);

int main(void)
{
    char arr1[20] = "initial";
    char arr2[25] = "second";

    foo(arr1); // <------- should change it to the string "second" upon scanf()

    printf("Test Return Value: %s\n",arr1); // <---- returns "initial" (the problem)

    printf("Enter a test value: ");
    scanf("%s", &arr1);

    printf("Test Return Value: %s\n",&arr1);

// ---------------------- this code is not part of the issue
fflush(stdin);
getchar();
return 0;
// ----------------------
}
void foo(char arr1[], char arr2[])
{
    // there will be many returned values

    printf("Enter a test value: ");
    scanf("%s", &arr1); // <---------- the problem function (input < 20 chars)
}

Answer 1

scanf("%s", &arr); // <---------- the problem function (input < 20 chars)

should be

scanf("%s", arr); // <---------- the problem function (input < 20 chars)

The perils of using the C io functions!