Exercise 1-1 (Hello - error messages)
| Chapter_1 Hello | Exercise_1-2 |
Exercise 1-1 K&R, p. 8
Exercise 1-1. Run the "hello, world" program on your system. Experiment with leaving out parts of the program, to see what error messages you get.
CONTENTS: hello1.c hello2.c hello3.c hello4.c hello5.c hello6.c hello7.c hello8.c hello9.c hello10.c hello11.c
Semicolon after #include directive
#include <stdio.h>; // no semicolon after directive
int main()
{
printf("Hello, world!\n");
}
/*
gcc hello1.c // Compiler gives a warning, but creates the executable:
hello1.c:1:19: warning: extra tokens at end of #include directive
1 | #include <stdio.h>; // no semicolon after directive
| ^
./a.out
Hello, world!
*/
Missing (commented out) #include <stdio.h>
//#include <stdio.h>
int main()
{
printf("Hello, world!\n");
}
/*
gcc hello2.c // compile
// Error message:
hello2.c: In function ‘main’:
hello2.c:5:3: warning: implicit declaration of function ‘printf’
[-Wimplicit-function-declaration] // line 5, column 3
5 | printf("Hello, world!\n");
| ^~~~~~
hello2.c:5:3: warning: incompatible implicit declaration of built-in function ‘printf’
hello2.c:1:1: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
+++ |+#include <stdio.h>
1 | //#include <stdio.h>
*/
Missing ending '>' after 'stdio.h'
#include <stdio.h
int main()
{
printf("Hello, world!\n");
}
/*
gcc hello3.c
hello3.c:1:18: error: missing terminating > character
1 | #include <stdio.h
| ^
*/
Missing '#' before 'include'
include <stdio.h>
int main()
{
printf("Hello, world!\n");
}
/*
gcc hello4.c
hello4.c:1:9: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘<’ token
1 | include <stdio.h>
| ^
*/
<stdio> not recognized, write <stdio.h>
#include <stdio>
int main()
{
printf("Hello, world!\n");
}
/*
gcc hello5.c
hello5.c:1:10: fatal error: stdio: No such file or directory
1 | #include <stdio>
| ^~~~~~~
compilation terminated.
*/
Missing terminating " for printf() argument
#include <stdio.h>
int main()
{
printf("Hello, world!\n);
}
/*
gcc hello6.c
hello6.c: In function ‘main’:
hello6.c:5:10: warning: missing terminating " character
5 | printf("Hello, world!\n);
| ^
hello6.c:5:10: error: missing terminating " character
5 | printf("Hello, world!\n);
| ^~~~~~~~~~~~~~~~~~
hello6.c:6:1: error: expected expression before ‘}’ token
6 | }
| ^
hello6.c:5:10: error: expected ‘;’ before ‘}’ token
5 | printf("Hello, world!\n);
| ^
| ;
6 | }
| ~
*/
Missing ending ')' for printf()
#include <stdio.h>
int main()
{
printf("Hello, world!\n";
}
/*
gcc hello7.c
hello7.c: In function ‘main’:
hello7.c:5:27: error: expected ‘)’ before ‘;’ token
5 | printf("Hello, world!\n";
| ^
| )
hello7.c:5:28: error: expected ‘;’ before ‘}’ token
5 | printf("Hello, world!\n";
| ^
| ;
6 | }
| ~
*/
Missing semicolon after printf()
#include <stdio.h>
int main()
{
printf("Hello, world!\n")
}
/*
gcc hello8.c
hello8.c: In function ‘main’:
hello8.c:5:28: error: expected ‘;’ before ‘}’ token
5 | printf("Hello, world!\n")
| ^
| ;
6 | }
| ~
*/
Missing ending '}' for main()
#include <stdio.h>
int main()
{
printf("Hello, world!\n");
//}
/*
gcc hello9.c
hello9.c: In function ‘main’:
hello9.c:5:3: error: expected declaration or statement at end of input
5 | printf("Hello, world!\n");
| ^~~~~~
*/
Missing main() function declaration
#include <stdio.h>
//int main()
{
printf("Hello, world!\n");
}
/*
gcc hello10.c
hello10.c:4:1: error: expected identifier or ‘(’ before ‘{’ token
4 | {
| ^
*/
Missing main() altogether
#include <stdio.h>
//int main()
//{
printf("Hello, world!\n");
//}
/*
gcc hello11.c
hello11.c:5:10: error: expected declaration specifiers or ‘...’ before string constant
5 | printf("Hello, world!\n");
| ^~~~~~~~~~~~~~~~~
*/
| Chapter_1 Hello | BACK_TO_TOP | Exercise_1-2 |
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