prog.c: In function ‘main’:
prog.c:2:9: error: unknown type name ‘FILE’
FILE *f;
^~~~
prog.c:3:13: warning: implicit declaration of function ‘fopen’ [-Wimplicit-function-declaration]
f = fopen("file","wb");
^~~~~
prog.c:3:11: warning: assignment makes pointer from integer without a cast [-Wint-conversion]
f = fopen("file","wb");
^
prog.c:4:9: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]
printf("%d",f != NULL);
^~~~~~
prog.c:4:9: warning: incompatible implicit declaration of built-in function ‘printf’
prog.c:4:9: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
prog.c:4:26: error: ‘NULL’ undeclared (first use in this function)
printf("%d",f != NULL);
^~~~
prog.c:4:26: note: each undeclared identifier is reported only once for each function it appears in
prog.c:5:9: warning: implicit declaration of function ‘fclose’ [-Wimplicit-function-declaration]
fclose(f);
^~~~~~