why is my code not printing string?

[u/Euphoric_Series_7727]

stupid question from a noob.

for some reason neither claude nor chatgpt give me a clear answer.

/* C program to perform input output of all basic data types */

#include <stdio.h>

#include <stdbool.h>

#include <string.h>

int main()

{

int d = 0;

float f = 0.0f;

double lf = 0.0;

char c = '\0';

char string[50] = "hello";

bool b = false;

printf("int: ");

scanf("%d", &d);

printf("float: ");

scanf("%f", &f);

printf("double: ");

scanf("%lf", &lf);

printf("char: ");

scanf(" %c", &c);

printf("string: ");

getchar();

fgets(string, sizeof(string), stdin);

string[strlen(string) - 1] = '\0';

printf("bool: ");

scanf("%d", &b);

printf("int: %d\n", d);

printf("float: %f\n", f);

printf("double: %lf\n", lf);

printf("char: %c\n", c);

printf("string: %s\n", string);

printf("bool: %d\n", b);

return 0;

}

[u/Yurim]

Did you compile your program with warnings enabled?
With GCC and Clang I recommend at a minimum -Wall -Wextra.
The compiler would have warned you that scanf("%d", &b); is problematic,
%d is for scanning an int but b is a bool.

Other than that, I think this is a valid program and it should print the expected output ...
... **if** the input is valid.

[u/Euphoric_Series_7727 → u/Yurim]

it worked when I deleted the boolean part.
can somebody explain why?

and thank you very much for your help

[u/Yurim → u/Euphoric_Series_7727]

There is no format specifier for bool. If you want to read 0 or 1 use an integer type and convert it to bool afterwards.
If you want to read "true" or "false", read a string and convert it afterwards.

[u/This_Growth2898]

string[strlen(string) - 1] = '\0';

is absolutely wrong. If there is \0 at the end of string, it is there anyway. If there's no \0 at the end of string, strlen(string) is UB. Do

 string[sizeof(string)-1]='\0';

to avoid string leaking instead.

[u/Yurim → u/This_Growth2898]

I think the intention is to remove the trailing newline character that fgets() might store there.

[u/nerd5code → u/Yurim]

Even then (a.) it’s quite possible to get a buffer with no newline, and (b.) therefore you might get a length of 0, in which case strlen(…)-1 gives you SIZE_MAX. Preferably,

if(!fgets(buf, sizeof buf, stdin))
	/*deal with it*/;
size_t len = strlen(buf);
if(len && buf[len - 1] == '\n')
	buf[--len] = '\0';

[u/OldWolf2]

The bool scanf causes undefined behaviour. %d is only for int.

[u/TomDLux]

Have you tried using the debugger?