Thread: User-Defined Static Library Not Linking Against Program

Hi, I am trying to create a static library for a small function I wrote called printfc which acts like printf except that it accepts additional arguments for color attributes. It is intended to work only on a bash console or any console that honors the particular escape codes I am using. I can compile and run it just fine when I compile printf.c into printfc.o and link it with my program. The problem comes in when I try to statically link libprintfc.a with my program, I get the dreaded "undefined reference to printfc." At the top, if it matters, I am using gcc (Ubuntu/Linaro 4.4.4-14ubuntu5) 4.4.5

Here's printfc.h

Code:

#ifndef PRINTFC_H
#define PRINTFC_H

#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <stdlib.h>

#define TEXT_NORMAL      0
#define TEXT_BOLD 1
#define TEXT_UNDERSCORE 4
#define TEXT_BLINKING 5 // Doesn't seem to work
#define TEXT_REVERSE_VIDEO 7
#define TEXT_CONCEALED 8

#define TEXT_FOREGROUND_BLACK 30
#define TEXT_FOREGROUND_RED 31
#define TEXT_FOREGROUND_GREEN 32
#define TEXT_FOREGROUND_YELLOW 33
#define TEXT_FOREGROUND_BLUE 34
#define TEXT_FOREGROUND_MAGENTA 35
#define TEXT_FOREGROUND_CYAN 36
#define TEXT_FOREGROUND_WHITE 37

#define TEXT_BACKGROUND_BLACK 40
#define TEXT_BACKGROUND_RED 41
#define TEXT_BACKGROUND_GREEN 42
#define TEXT_BACKGROUND_YELLOW 43
#define TEXT_BACKGROUND_BLUE 44
#define TEXT_BACKGROUND_MAGENTA 45
#define TEXT_BACKGROUND_CYAN 46
#define TEXT_BACKGROUND_WHITE 47

void printfc(int style, int fcolor, int bcolor, const char* format, ...);
char* strchr_many(const char*, const char*);
char* strrchr_many(const char*, const char*);

#endif

Here's printfc.c

Code:

#include "printfc.h"

// Prints out a formatted string subject to the text attributes passed.
// New lines, tabs, vertical tabs, and form feeds will not be colored.
//
// NOTE: Format arguments passed are not subject to this rule. That means
// it's possible to pass a string containing such white space as new lines
// tabs, vertical tabs or form feeds, but those will be improperly colored.
void printfc(int style, int fcolor, int bcolor, const char* format, ...)
{
	char* _format = strdup(format);
	char* _begin = _format;
	char* _end = _format + strlen(_format) - 1;
	char* _line = strchr_many(_begin, "\n\f\t\v");
	char t;

	va_list args;
	va_start(args, format);

	while(_begin < _end && _begin != NULL)
	{
		if(_line != NULL)
		{
			t = *_line;
			*_line = 0;
		}

		// Escape our color attributes
		if(bcolor != 0)
			printf("%c[%d;%d;%dm", 0x1B, style, fcolor, bcolor);
		else
			printf("%c[%d;%dm", 0x1B, style, fcolor);

		// Invoke the real printf()
		vprintf(_begin, args);

		// End our use of color attributes
		printf("%c[%dm", 0x1B, 0);

		if(_line == NULL)
			break;

		// Actually do the new line
		printf("%c", t);

		// Advance to the next new line
		_begin = _line + 1;
		if(_begin > _end) 
			break;

		_line = strchr_many(_begin, "\n\f\t\v");
	}

	va_end(args);
	free(_format);
}

// Same as strchr() except it returns a pointer to the first character
// in the string that matches ANY of the characters in cs.
char* strchr_many(const char* string, const char* cs)
{
	int x = strlen(string);
	int y = strlen(cs);
	int i, j;

	for(i = 0; i < x; ++i)
		for(j = 0; j < y; ++j)
			if(string[i] == cs[j])
				return (char*)string + i;

	return NULL;
}

// Same as strrchr() except it returns a pointer to the last character
// in the string that matches ANY of the characters in cs.
char* strrchr_many(const char* string, const char* cs)
{
	int x = strlen(string);
	int y = strlen(cs);
	int i, j;

	for(i = x - 1; i >= 0; i--)
		for(j = 0; j < y; ++j)
			if(string[i] == cs[j])
				return (char*)string + i;

	return NULL;
}

Here's main.c

Code:

#include "printfc.h"

int main(int argc, char** argv)
{
	printfc(	TEXT_BOLD, 
				TEXT_FOREGROUND_BLUE,
				TEXT_BACKGROUND_RED, "Hello,\n\tthere\v World!\fHow's it going?\n");

	printf("Hello,\n\tthere\v World!\fHow's it going?\n");
	return 0;
}

To generate the static library, I am running these commands:

Code:

gcc -c printfc.c -o printfc.o
ar rcs libprintfc.a printfc.o

My attempt to compile and link with it was met with

Code:

gcc -L. -lprintfc main.c -o ./run2
/tmp/ccBlotsy.o: In function `main':
main.c:(.text+0x29): undefined reference to `printfc'
collect2: ld returned 1 exit status
make: *** [static-link] Error 1

This makes no sense to me since

Code:

nm libprintfc.a
printfc.o:
                 U free
                 U printf
0000000000000000 T printfc
                 U putchar
0000000000000252 T strchr_many
                 U strdup
                 U strlen
00000000000002d8 T strrchr_many
                 U vprintf

I feel that I am just making a simple mistake. I would be grateful if someone would point me in the right direction.

> gcc -L. -lprintfc main.c -o ./run2
Try

gcc main.c -o ./run2 -L. -lprintfc

You need unresolved symbols from main.c to exist at the point you scan the library for those unresolved symbols.