C/C++：GCC/G++ -Wl,-soname

1. mymath.h：

#ifndef _MYMATH_H
#define _MYMATH_H

int add(int, int);
int sub(int, int);
int mul(int, int);
int div(int, int);

#endif

2. mymath.c:

#include "mymath.h"

int add(int a, int b)
{
    return a + b;
}

int sub(int a, int b)
{
    return a - b;
}

int mul(int a, int b)
{
    return a * b;
}

int div(int a, int b)
{
    return a / b;
}

3. main.c

#include <stdio.h>
#include <unistd.h>

#include "mymath.h"

int main()
{
    int a = 20;
    int b = 5;

    printf("add(%d, %d)=%d\n", a, b, add(a, b));
    printf("sub(%d, %d)=%d\n", a, b, sub(a, b));
    printf("mul(%d, %d)=%d\n", a, b, mul(a, b));
    printf("div(%d, %d)=%d\n", a, b, div(a, b));

    return 0;
}

4. makefile:

SRC = mymath.c
OBJS = $(SRC:%.c=%.o)

LIB = libmymath.so
SONAME = $(LIB)
CC = gcc -std=gnu99 -fPIC
CFLAGS = -g -O2 -Wall -Wextra
LDFLAGS = -Wl,-soname,$(SONAME)
DEPLIBS =
SHARED = -shared

.c.o:
    $(CC) $(CFLAGS) -o $@ -c $<
    @echo "Compile $< to $@ OK"

all:
    @make libmymath

libmymath: $(OBJS)
    $(CC) -o $(LIB) $(SHARED) $(LDFLAGS) $(OBJS) $(DEPLIBS)

clean:
    @rm -f $(OBJS)
    @rm -f $(LIB)

.PHONY: all clean

make
gcc -o main main.c -lmymath -L.
ldd main
readelf -d libmymath.so
修改makefile中SONAME = libmymath.1.so
重新運行程序
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