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Quest: page 8

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Run the "hello, world" program on your system. Experiment with leaving out parts of the program, to see what error messages you get:

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hello world program

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

int main() {
    printf("hello world\n");
    return EXIT_SUCCESS;
}

If i compile the program and run it. It will print me hello world.

gcc main.c && ./a.out

omit the include:

main.c: In function ‘main’:
main.c:3:5: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]
    3 |     printf("hello world\n");
      |     ^~~~~~
main.c:1:1: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
  +++ |+#include <stdio.h>
    1 |
main.c:3:5: warning: incompatible implicit declaration of built-in function ‘printf’ [-Wbuiltin-declaration-mismatch]
    3 |     printf("hello world\n");
      |     ^~~~~~
main.c:3:5: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
main.c:4:12: error: ‘EXIT_SUCCESS’ undeclared (first use in this function)
    4 |     return EXIT_SUCCESS;
      |            ^~~~~~~~~~~~
main.c:1:1: note: ‘EXIT_SUCCESS’ is defined in header ‘<stdlib.h>’; did you forget to ‘#include <stdlib.h>’?
  +++ |+#include <stdlib.h>
    1 |
main.c:4:12: note: each undeclared identifier is reported only once for each function it appears in
    4 |     return EXIT_SUCCESS;
      |            ^~~~~~~~~~~~

omit one semicolon:

main.c: In function ‘main’:
main.c:4:37: error: expected ‘;’ before ‘return’
    4 | int main() { printf("hello world\n") return EXIT_SUCCESS; }
      |                                     ^~~~~~~
      |

omit curly braces at the end:

main.c: In function ‘main’:
main.c:6:3: error: expected declaration or statement at end of input
    6 |   return EXIT_SUCCESS;
      |   ^~~~~~

note

A compiler will give good details on what might be wrong.