类中哪些函数能设为内联函数？ - 编程论坛

#2

flyingcat2010-08-09 18:45

- -内联函数，这个函数是反复多次被调用，为了提高程序的效率，会使用内联函数
不过内联函数的要求是，只能包含简单的运算（我记得代码最好也不要超过三行），什么循环、switch之类的都不能有，只能是简单的函数
你说的undefined reference to，应该是指后面那个变量未定义

#3

feng000552010-08-09 20:33

//stonewt.h
#ifndef STONEWT_H_
#define STONEWT_H_

class Stonewt {
private:
    enum {Lbs_per_stn = 14};
    int stone;
    double pds_left;
    double pounds;
public:
    Stonewt(double lbs);
    Stonewt(int stn, double lbs);
    Stonewt();
    ~Stonewt();
    void show_lbs()const;
    void show_stn()const;
};

#endif

//stonewt.cc
#include <iostream>
#include "stonewt.h"

Stonewt::Stonewt(double lbs) {
    stone = int(lbs) / Lbs_per_stn;
    pds_left = int(lbs) % Lbs_per_stn + lbs - int(lbs);
    pounds = lbs;
}

Stonewt::Stonewt(int stn, double lbs) {
    stone = stn;
    pds_left = lbs;
    pounds = stn * Lbs_per_stn + lbs;
}

Stonewt::Stonewt() {
    stone = pounds = pds_left = 0;
}

Stonewt::~Stonewt() {}

void Stonewt::show_stn()const {
    std::cout << stone << " stone, " << pds_left << " pounds\n";
}

void Stonewt::show_lbs()const {
    std::cout << pounds << "  pounds\n";
}

#4

feng000552010-08-09 20:37

#include <iostream>
#include "stonewt.h"

void display(const Stonewt & st, int n);

int main(void) {
    Stonewt pavarotti = 260;
    Stonewt wolfe(285.7);
    Stonewt taft(21, 8);

    std::cout << "The tenor weighed ";
    pavarotti.show_stn();
    std::cout << "The detective weighted ";
    wolfe.show_stn();
    std::cout << "The President weighted ";
    taft.show_lbs();
    pavarotti = 265.8;
    taft = 325;
    std::cout << "After dinner, the tenor weighted ";
    pavarotti.show_stn();
    std::cout << "After dinner, the President weighed ";
    taft.show_lbs();
    display(taft, 2);
    std::cout << "The wrestler weighed even more.\n";
    display(422, 2);
    std::cout << "No stone left unearned\n";
    return 0;
}

void display(const Stonewt & st, int n) {
    for (int i = 0; i < n; ++i) {
        std::cout << "Wow! ";
        st.show_stn();
    }
}

#5

feng000552010-08-09 20:40

stonewt.cc中除了没用到的Stonewt()外，为什么全都不能设置为内联函数？

#6

feng000552010-08-09 21:53

对不起，是我搞错了：内联函数要求在每个使用它们的文件中
都对其进行定义，而我却把它们放到了不是头文件的文件中，在主函数
文件中又没包含它们，所以才出错！

原来是我概念没弄清楚！

#7

feng000552010-08-09 21:55

多谢2楼，虽没有提到这点，所以给你10分吧!

#8

feng000552010-08-09 21:58

给不了10，给20吧