Static Function Example

/* test-module.c */
static int privateValue = 15;

static int getValue() {
    return privateValue;
}

static void setValue(int val) {
    privateValue = val;
}

int getPrivateValue() {
    return getValue();
}

void setPrivateValue(int val) {
    setValue(val);
}

/* main.c */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define valueOf(f, x) printf("Test: "#x" = %"#f"\n", x)

int main(int argc, char **argv) {
    setValue(5); /* undefined reference to `setValue' */
    valueOf(d, getValue()); /* undefined reference to `getValue' */

    setPrivateValue(10);
    valueOf(d, getPrivateValue());

    exit(EXIT_SUCCESS);
}

/* Compilation */
gcc -g -O2 -o testing test-module.c testing.c