The program returns an error when I try to generate a random character. warning C4242:

Question

warning C4242: 'function': conversion from 'time_t' to 'unsigned int', possible loss of data

#include<stdio.h>
#include<time.h>
#include<stdlib.h>

int main(void)
{
    srand(time(0));
    int lucky = (rand() % 26) + 65;

    printf("> %d", lucky);

    return 0;
}

I am expecting the program to output a random letter between uppercase A to uppercase Z.

The srand function seems to be working with other programs but not here. Not sure why.

Why are you expecting that? ` %d"` outputs a number, not a character. — , Mar 25 '19 at 21:19
`time` returns a `time_t`. `time_t` is signed and isn't necessarily the same size as an `int`. `srand` expects an unsigned `int`, so you've got two strikes against you. The compiler is warning you that some of the time could be lost. — user4581301, Mar 25 '19 at 21:20
`printf("> %d", lucky);` prints an integer instead of a character. — drescherjm, Mar 25 '19 at 21:21
@NeilButterworth That's just me trying different thing to see if it works. I will correct it now. — mattmallow, Mar 25 '19 at 21:57
By editing your question after receiving answers, you have made the existing answer almost completely irrelevant. — paddy, Mar 25 '19 at 22:01
@JohnColeman Thank you guys for that, I will note that down. — mattmallow, Mar 25 '19 at 22:05

score 2 · Answer 1 · answered Mar 25 '19 at 21:21

2

You are instructing printf to output the value as an integer. To output a character, you need to use %c format specifier.

It is also preferable to use character constants instead of hard-coded numbers, for clarity. And, while not strictly necessary for printf, your lucky type should probably be char since you intend it to represent a character:

char lucky = (rand() % 26) + 'A';
printf("> %c", lucky);

answered Mar 25 '19 at 21:21

paddy

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Might be worth an edit to hammer home the point that the problem the asker is facing has absolutely nothing to do with the compiler warning. – user4581301 Mar 25 '19 at 21:25
This is just me trying different things, sorry new to this. – mattmallow Mar 25 '19 at 21:55
But what bothers me is the error:"error C2220: warning treated as error - no 'object' file generated" which is indicating that my "srand(time(0))" is wrong? I believe it doesn't have anything wrong with the rest of the code? – mattmallow Mar 25 '19 at 21:56
Regarding "warning treated as error", yes that's an issue for you. It will cause compilation to fail if any warnings are encountered. Generally, it's a good idea to keep this enabled because warnings are there for a reason. Just fix the warning, which you can do after reviewing the question that was referenced as already providing an answer. – paddy Mar 25 '19 at 21:59
@paddy Cheers, thanks for that. – mattmallow Mar 25 '19 at 22:00

The program returns an error when I try to generate a random character. warning C4242:

1 Answers1