NAME

get_long - prompt a user for an long

get_long - prompts user for a line of text from stdin and returns the equivalent long

SYNOPSIS

Header File

#include <cs50.h>

Prototype

long get_long(string prompt, ...);

#include <cs50.h>

long get_long(const char *format, ...);

DESCRIPTION

This function prompts the user for a long. If the user inputs anything other than an long (or a value that cannot fit in an long), the function prompts the user again.

This function expects at least one argument, prompt. If prompt contains any format codes, a la printf, this function accepts additional arguments as well, one per format code.

Prompts user for a line of text from standard input and returns the equivalent long; if the text does not represent a long or would cause overflow, user is reprompted.

The prompt is formatted like printf(3).

RETURN VALUE

This function returns the user’s input as a long.

Returns the long equivalent to the line read from stdin in [LONG_MIN, LONG_MAX). If line can’t be read, returns LONG_MAX.

EXAMPLE

#include <cs50.h>
#include <stdio.h>

int main(void)
{
    long l = get_long("Input:  ");
    printf("Output: %li\n", l);
}

/**
 * Returns the difference of two longs read from stdin, or LONG_MAX if there was an error.
 */
long subtract_longs(void)
{
    // read long from stdin
    long i = get_long("Enter a long: ");

    // make sure we read one successfully
    if (i == LONG_MAX)
    {
        return LONG_MAX;
    }

    long j = get_long("What do you want to subtract from %ld? ", i);

    if (j == LONG_MAX)
    {
        return LONG_MAX;
    }

    return i - j;
}