Initializing and scanning a variable in C

Question

can anyone please help me out with this in C language for ex:

int a = scanf("%d", &a);

doesn't assign the input value to a, but instead gives zero only always.

but this works as intended:

int a;
int a = scanf("%d", &a);

`scanf` returns the number of fields parsed, **not** any parsed value. — wohlstad, Jun 22 '22 at 15:35
You should read the documentation for functions you're using — klutt, Jun 22 '22 at 15:47
`int a; int a = scanf(...);` defines variable `a` twice, which is invalid. Did you mean `int a; a = scanf(...);`? — Ian Abbott, Jun 22 '22 at 15:50

score 0 · Accepted Answer · answered Jun 22 '22 at 15:47

int a;
int a = scanf("%d", &a);

Does not compile because you redefine the variable a twice in the same scope.

scanf("%d", &a) attempts to parse the characters from stdin as the representation of an int and if successful stores the value to a and returns 1, otherwise returns EOF at end of file and 0 if characters are present but do not represent an int value in decimal representation.

Here is an example:

#include <stdio.h>

int main() {
    int a, c, res;
    for (;;) {
        res = scanf("%d\n", &a);
        switch (res) {
          case 1:    printf("value input is %d\n", a);
                     break;
          case 0:    printf("input is not a number\n");
                     break;
          case EOF:  printf("end of file detected\n");
                     return 0;
        }
        // read and discard the rest of the input line
        while ((c = getchar()) != EOF && c != '\n')
            continue;
    }
}

Initializing and scanning a variable in C

1 Answers1