Read an Integer from the User

[Baljeet]

Read an Integer from the User, Part 1

Obtaining user input can be done in many surprisingly different ways. This code is somewhere in the middle: safer than scanf("%d", &n), but not bulletproof. It is meant to be a simple but relatively safe demonstration.

The function mygeti reads user input from the stdin into a string using fgets. Then it attempts to convert this string to an integer using sscanf. If both functions succeed, a 1 is returned; if either fails, a 0 is returned.

[COLOR="Green"]#include [B]<[/B]stdio.h[B]>[/B][/COLOR]

[COLOR="Blue"]int [/COLOR][COLOR="Red"]mygeti[/COLOR]([COLOR="Blue"]int [/COLOR]*result)
{
        [COLOR="Blue"]char [/COLOR]buff [ [COLOR="Teal"]13 [/COLOR]]; [COLOR="Silver"]/* signed 32-bit value, extra room for '\n' and '\0' */[/COLOR]
        [COLOR="Blue"]return [/COLOR][COLOR="Red"]fgets[/COLOR](buff, [COLOR="Blue"]sizeof [/COLOR]buff, [COLOR="DarkOrchid"]stdin[/COLOR]) && [COLOR="Red"]sscanf[/COLOR](buff, [COLOR="Teal"]"%d"[/COLOR], result) == [COLOR="Teal"]1[/COLOR];
}

[COLOR="Blue"]int [/COLOR][COLOR="Red"]main[/COLOR]([COLOR="Blue"]void[/COLOR])
{
        [COLOR="Blue"]int [/COLOR]value;
        [COLOR="Blue"]do [/COLOR]{
                fputs([COLOR="Teal"]"Enter an integer: "[/COLOR], [COLOR="DarkOrchid"]stdout[/COLOR]);
                fflush([COLOR="DarkOrchid"]stdout[/COLOR]);
        } [COLOR="Blue"]while [/COLOR]( ![COLOR="Red"]mygeti[/COLOR](&value) );
        [COLOR="Red"]printf[/COLOR]([COLOR="Teal"]"value = %d\n"[/COLOR], value);
        [COLOR="Blue"]return [/COLOR][COLOR="Teal"]0[/COLOR];
}

[COLOR="Silver"]/* my output
Enter an integer: one
Enter an integer:
Enter an integer: 42
value = 42

Enter an integer: 24f
value = 24

Enter an integer:    125 help
value = 125
*/[/COLOR]

Leading whitespace, and other trailing characters are some things not handled. Those issues are handled in

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can be done similarly.

All Credits goes to one who really made this...