问错误:动态符号检索错误：./构建/发布/obj.Target/math.so:未定义符号: add。linux系统中的节点-ffi

EN

#include "math.h"

int add(int x, int y)
{
  return x + y;
}

int minus(int x, int y)
{
  return x - y;
}

int multiply(int x, int y)
{
  return x * y;
}

int add(int a, int b);
int minus(int a, int b);
int multiply(int a, int b);

var ffi = require('ffi');
var ref = require('ref');
var int = ref.types.int;

var platform = process.platform;
var mathlibLoc = null;

if (platform === 'win32'){
    mathlibLoc = './math.dll';
}else if(platform === 'linux'){
    mathlibLoc = './build/Release/obj.target/math.so';
}else if(platform === 'darwin'){
    mathlibLoc = './math.dylib'
}else{
    throw new Error('unsupported plateform for mathlibLoc')
}

var math = ffi.Library(mathlibLoc, {
    "add": [int, [int, int]],
    "minus": [int, [int, int]],
    "multiply": [int, [int, int]]
});

module.exports = math;

var math = require('./math');
var result = null;

result = math.add(5, 2);
console.log('5+2='+result);

result = math.minus(5, 2);
console.log('5-2='+result);

result = math.multiply(5, 2);
console.log('5*2='+result);