Run C or C++ file as a script

Question

So this is probably a long shot, but is there any way to run a C or C++ file as a script? I tried:

#!/usr/bin/gcc main.c -o main; ./main

int main(){ return 0; }

But it says:

./main.c:1:2: error: invalid preprocessing directive #!

Answer 1

CINT:

CINT is an interpreter for C and C++ code. It is useful e.g. for situations where rapid development is more important than execution time. Using an interpreter the compile and link cycle is dramatically reduced facilitating rapid development. CINT makes C/C++ programming enjoyable even for part-time programmers.

Answer 2

For C, you may have a look at tcc, the Tiny C Compiler. Running C code as a script is one of its possible uses.

Answer 3

$ cat /usr/local/bin/runc
#!/bin/bash
sed -n '2,$p' "$@" | gcc -o /tmp/a.out -x c++ - && /tmp/a.out
rm -f /tmp/a.out

$ cat main.c
#!/bin/bash /usr/local/bin/runc

#include <stdio.h>

int main() {
    printf("hello world!\n");
    return 0;
}

$ ./main.c
hello world!

The sed command takes the .c file and strips off the hash-bang line. 2,$p means print lines 2 to end of file; "$@" expands to the command-line arguments to the runc script, i.e. "main.c".

sed's output is piped to gcc. Passing - to gcc tells it to read from stdin, and when you do that you also have to specify the source language with -x since it has no file name to guess from.

Answer 4

Since the shebang line will be passed to the compiler, and # indicates a preprocessor directive, it will choke on a #!.

What you can do is embed the makefile in the .c file (as discussed in this xkcd thread)

#if 0
make $@ -f - <<EOF
all: foo
foo.o:
   cc -c -o foo.o -DFOO_C $0
bar.o:
   cc -c -o bar.o -DBAR_C $0
foo: foo.o bar.o
   cc -o foo foo.o bar.o
EOF
exit;
#endif

#ifdef FOO_C

#include <stdlib.h>
extern void bar();
int main(int argc, char* argv[]) {
    bar();
    return EXIT_SUCCESS;
}

#endif

#ifdef BAR_C
void bar() {
   puts("bar!");
}
#endif

The #if 0 #endif pair surrounding the makefile ensure the preprocessor ignores that section of text, and the EOF marker marks where the make command should stop parsing input.

Answer 5

Variatn of John Kugelman can be written in this way:

#!/bin/bash
t=`mktemp`
sed '1,/^\/\/code/d' "$0" | g++ -o "$t" -x c++ - && "$t" "$@"
r=$?
rm -f "$t"
exit $r


//code
#include <stdio.h>

int main() {
    printf("Hi\n");
    return 0;
}