A C program which is also a valid bash script, and vice versa.

shellandc.c

#include <stdio.h>
#define $x ,x
#define $i ,i
#define eval int
#define read scanf
#define $scanfpat "%d", &
#define $(x) ,(x)
#define $open (
#define $close )
#define do {
#define done }
#define then {
#define fi }
#define else } else {
main() {
    eval i=0;
    eval x=7;
    read $open $scanfpat x $close;
    for (( i = 0 $close; i < 5; $open i++ ))
    do
        printf $open "%d\n" $((x+i)) $close;
    done
    if (( x % 2 ))
    then
        printf $open "%d is odd\n" $x $close;
    fi

    for (( i = 1 $close; i <= 100; $open i++ ))
    do
        if (( i % 3 ))
        then
            if (( i % 5 ))
            then
                printf $open "%d\n" $i $close;
            else
                printf $open "buzz\n" $close;
            fi
        else
            if (( i % 5 ))
            then
                printf $open "fizz\n" $close;
            else
                printf $open "fizzbuzz\n" $close;
            fi
        fi
    done
    return 0;
}

#if 0
main
#endif