c++:if 语句无法正常运行，并继续执行无效输出

c++ : The if statement not functioning correctly and proceeds to Invalid output

本文关键字：继续 执行 无效 输出 正常运行 if 语句 c++      更新时间：2023-10-16

刚开始学习c ++并尝试制作自动订购系统，但是在继续使用它之前尝试运行时，我遇到了这个问题：

#include <iostream>
using namespace std;
char acoustic, fender, hartwood, electric, gibson, ibanez, drums, pearl, 
roland, piano, casio;
char rolandpi, equip, string, headphone, amp, mixer, micro, tuner, pick, 
music, Yes, No;
int pay1 = 0, pay2 = 0;
int main()
{
cout << "Welcome to the Music Shop" << endl <<endl;
cout << "a. Acoustic Guitar" << endl;
cout << "a.1 Fender Acoustic Guitar   - P6,900.00" << endl;
cout << "a.2 Hartwood Acoustic Guitar - P6,300.00" << endl <<endl;
cout << "b. Electric Guitar" << endl;
cout << "b.1 Gibson Electric Guitar   -P8,500.00" << endl;
cout << "b.2 Ibanez Electric Guitar   -P25,000.00" << endl <<endl;
cout << "c. Drums" << endl;
cout << "c.1 Pearl Drum Kits          -P27,000.00" << endl;
cout << "c.2 Roland Electronic Drums  -P24,000.00" << endl <<endl;
cout << "d. Piano" << endl;
cout << "d.1 Casio Digital Piano      -P19,000.00" << endl;
cout << "d.2 Roland Piano             -P120,000.00" << endl <<endl;
cout << "e. Music Equipments" << endl;
cout << "e.1 Guitar String            -P113.00" << endl;
cout << "e.2 Headphones               -P1,600.00" << endl;
cout << "e.3 Amplifier                -P2,800.00" << endl;
cout << "e.4 Digital Mixer            -P4,750.00" << endl;
cout << "e.4 Vocal Microphone         -P860.00" << endl;
cout << "e.5 Guitar Tuner             -P537.00" << endl;
cout << "e.6 Guitar Pick              -P360.00" << endl <<endl;
cout << "Choose the music instrument or equipment you want to buy: ";
cin >> music;
switch (music)
{
case 'a':
cout<< "Acoustic Guitar" << endl;
cout<< "1. Fender Acoustic Guitar   - P6,900.00" << endl;
cout<< "2. Hartwood Acoustic Guitar - P6,300.00" << endl <<endl;
cout<<"Choose from the available Acoustic Guitars:";
cin>>acoustic;
if (acoustic == 1){
cout<<"Enter your payment:";
cin>>pay1;
if (pay1=6900){
cout<<"You have succesfully purchased Fender Acoustic Guitar"<<endl;
}
else if (pay1>6900){
pay1 -= 6900;
cout<<"Your change is:"<<pay1<<endl;
}
else (pay1<6900);
{
cout<<"You do not have enough money"<<endl;
}
}
else if (acoustic == 2){
cout<<"Enter your payment:";
cin>>pay1;
if (pay1=6300){
cout<<"You have succesfully purchased Fender Acoustic Guitar"<<endl;
}
else if (pay1>6300){
pay1 -= 6300;
cout<<"Your change is:"<<pay1<<endl;
}
else (pay1<6300);
{
cout<<"You do not have enough money"<<endl;
}
}
else {
cout<<"Invalid"<<endl;
}
}
}

我已经检查了我的if else语句，找不到问题所在。

从"从可用的原声吉他中选择"输入1或2后，它继续进入"无效"。

你在这里读到char：

cout << "Choose from the available Acoustic Guitars:";
cin >> acoustic;

但是，您稍后将其与一行int进行比较：

if (acoustic == 1) {

相反，这应该是：

if (acoustic == '1') {

还有这个：

if (pay1 = 6900) {

应该是：

if (pay1 == 6900) {

因为否则无论输入什么，您都会得到不正确的输出，因为pay1 = 6900将pay1设置为6900并返回6900，这被隐式转换为true。

还有这一行：

else (pay1 < 6900);

需要更改为

else if (pay1 < 6900)

因为否则(pay1 < 6900)不是if语句的条件，而是(pay1 < 6900);else情况下发生的情况(它只是计算一个布尔值并丢弃它(，导致始终打印以下"You do not have enough money"消息。

@Blaze非常感谢你，现在我几乎完成了，现在我在输入是或否后遇到是或否的问题，程序刚刚结束，我不知道它有什么问题>.<</p> 

cout<<"nWould you like to buy an Electric Guitar?"<<endl;
cout<<"Yes or No?"<<endl;
cin>>answer;
if (answer == Yes){
cout<< "Electric Guitar" << endl;
cout<< "1. Gibson Electric Guitar   -P8,500.00" << endl;
cout<< "2. Ibanez Electric Guitar   -P25,000.00" << endl <<endl;
cout<<"Choose from the available Electric Guitars:";
cin>>electric;
if (electric=='1'){
cout<<"Enter your payment:";
cin>>pay2;
if (pay2==8500){
cout<<"You have succesfully purchased Fender Acoustic Guitar"<<endl;
}
else if (pay2>8500){
pay2 -= 8500;
cout<<"Your change is:"<<pay2<<endl;
}
else if(pay2<8500)
{
cout<<"You do not have enough money"<<endl;
}   
}
else if (electric=='2'){
cout<<"Enter your payment:";
cin>>pay2;
if (pay2==25000)
{
cout<<"You have succesfully purchased Fender Acoustic Guitar"<<endl;
}
else if (pay2>25000){
pay2 -= 25000;
cout<<"Your change is:"<<pay2<<endl;
}
else if (pay2<25000)
{
cout<<"Invalid"<<endl;
}   
}
else {
cout<<"Invalid";
}
} 
else if (No){
cout<<"Thank you for checking our other products";
}
}
}

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