bf2c.c

#include <stdio.h>

void print_prelude(FILE *output);

int main(int argc, char **argv) {
    FILE *src = NULL;
    FILE *output;
    if (argc != 2) return -1;
    char op;

    src = fopen(argv[1], "r");
    output = fopen("out.c", "w");

    print_prelude(output);

    while (!feof(src)) {
        op = fgetc(src);
        switch(op) {
            case '>': fputs("++ptr;\n", output); break;
            case '<': fputs("--ptr;\n", output); break;
            case '+': fputs("++*ptr;\n", output); break;
            case '-': fputs("--*ptr;\n", output); break;
            case '.': fputs("putchar(*ptr);\n", output); break;
            case ',': fputs("*ptr = getchar();\n", output); break;
            case '[': fputs("while (*ptr) {\n", output); break;
            case ']': fputs("}\n", output); break;
        }
    }

    fputs("return 0;\n}", output);
    fclose(src);
    fclose(output);

    return 0;
}

void print_prelude(FILE *output) {
    fputs(
            "#include <stdio.h>\n"
            "int main(void) {\n"
            "\tchar array[30000] = {0};\n"
            "\tchar *ptr = array;\n"
            "\n",
            output
    );
}