input_only_integer_v2.c

/*

    input_only_integer_v2.c

    Function that allows user to input only integer value.


    https://www.tutorialspoint.com/cprogramming/c_data_types.htm


    You can find all my C programs at Dragan Milicev's pastebin:

    https://pastebin.com/u/dmilicev

*/

#include <stdio.h>

// Function that allows user to input only integer value.
int input_only_integer( char *text, int *integer_number )
{
    int c;
    char terminator;

    while(1)                    // an infinite loop that exits with if condition
    {
        printf("%s", text);     // print prompt text

        // On success, the function scanf() returns the number
        // of items of the argument list successfully read.
        // If scanf() read two elements, integer and char, and return 2
        // and if second element terminator is enter '\n'
        // then first element is integer.
        if( scanf("%d%c", integer_number, &terminator) == 2 && terminator == '\n' )
            return(*integer_number);

        // fflush(stdin);       // flushes the input buffer of a stream,
        // but gives undefined behavior. Alternative is:
        // while ( ( c = getchar() ) != EOF && c != '\n' );
        // or:

        while ( ( c = getchar() ) != '\n' );

    } // while(1)
} //input_only_integer()


int main(void)
{
    int integer_number;

    input_only_integer("\n Enter integer number: ", &integer_number);

    printf("\n Entered integer number is %d \n", integer_number);


    return 0;

} // main()