如何解决这个问题：C++ switch语句

Question

我有我的switch语句的问题// number of crowns和// frame color

这是我的输出

我怎样才能让我的cout输出frame_color和number_crowns（上// number of crowns和// frame color）？

BTW即时通讯使用CodeBlocks

#include <iostream> 
#include <iomanip> 
using namespace std; 

int main() 
{ 
    int length, width, number_crowns; 
    double cost; 
    int frameType; 
    int yes_no; 
    int colorSelection; 
    string frame_color; 
    string type; 

    cout << "Input length and width of the picture: "; 
    cin >> length >> width; 

    cout << "1(spacebar)regular" << endl 
     << "2(spacebar)fancy" << endl 
     << "(regular/fancy)Enter type of frame: "; 
    cin >> frameType >> type; 

    cout << "1 = with" << endl 
     << "2 = without" << endl 
     << "(with/without)With color/Without?"; 
    cin >> colorSelection; 

    cout << "1 = yes" << endl 
     << "2 = no" << endl 
     << "(yes/no)Do you want to put crowns? "; 
    cin >> yes_no; 

    cost = (2 * 0.1) * (length + width);    // cost in length and width of the frame 
    cost += (0.02 * (length * width));     // cost per square inch 

    switch(frameType) 
    {         // type of frame 
    case '1': 
     cost += 0.15; 
     break; 
    case '2': 
     cost += 0.25; 
     break; 
    default: 
     cout << "wrong input!"; 
    } 

    switch(colorSelection) 
    {       // frame color 
    case '1': 
     cost += 0.10; 
     cout << "Enter desired frame color: "; 
     cin >> frame_color; 
     break; 
    case '2': 
     cost += 0; 
     break; 
    default: 
     cout << "wrong input!"; 
    } 

    switch(yes_no) 
    {         // number of crowns 
    case '1': 
     cout << "Input number of crowns: "; 
     cin >> number_crowns; 
     cost += (number_crowns * 0.35); 
     break; 
    case '2': 
     cost =+ 0; 
     break; 
    default: 
     cout << "wrong input!"; 
    } 

    cout << endl; 
    cout << "\n\nFrame type: " << type << "\n" << endl; 
    cout << "Frame colour: " << frame_color << "\n" << endl; 
    cout << "Total frame cost: " << cost << "\n" << endl; 
} 

非常感谢！

最新升级程序w^*** wahahaha

我怎样才能让我的cout输出frame_color和number_crowns（上// number of crowns和// frame color）？

#include <iostream> 

using namespace std; 

int main() 
{ 
    int length, width, number_crowns; 
    double cost; 
    char frameType; 
    char yes_no; 
    char colorSelection; 
    string frame_color; 
    string type; 

    cout << "Input length and width of the picture: "; 
    cin >> length >> width; 

    cout << "(regular/fancy) Enter type of frame: "; 
    cin >> frameType >> type; 

    cout << "(with/without) With color/Without?"; 
    cin >> colorSelection; 

    cout << "(yes/no) Do you want to put crowns? "; 
    cin >> yes_no; 

    cost = (2 * 0.1) * (length + width);    // cost in length and width of the frame 
    cost += (0.02 * (length * width));     // cost per square inch 

    cout << "\nFrame type: " << frameType << type << "\n" << endl; 
    switch(frameType) 
    {         // type of frame 
    case 'regular': 
     cost += 0.15; 
     break; 
    case 'fancy': 
     cost += 0.25; 
     break; 
    default: 
     cout << "wrong input!"; 
    } 

    cout << "\nFrame colour: " << frame_color << "\n" << endl; 
    switch(colorSelection) 
    {       // frame color 
    case 'with': 
     cost += 0.10; 
     cout << "Enter desired frame color: "; 
     cin >> frame_color; 
     break; 
    case 'without': 
     cost += 0; 
     break; 
    default: 
     cout << "wrong input!"; 
    } 

    switch(yes_no) 
    {         // number of crowns 
    case 'yes': 
     cout << "Input number of crowns: "; 
     cin >> number_crowns; 
     cost += (number_crowns * 0.35); 
     break; 
    case 'no': 
     cost =+ 0; 
     break; 
    default: 
     cout << "wrong input!"; 
    } 

    cout << endl; 
    cout << "\nTotal frame cost: " << cost << "\n" << endl; 
} 

最新的输出

Answer 1

你的变量frameType，yes_no和colorSelection被声明为int和你正在做针对char比较在switch。

您应该删除引号。

例如为：

cout<<"My frame type: "<<frameType<<endl; 
switch(frameType) 
{         // type of frame 
case 1: 
    cost += 0.15; 
    break; 
case 2: 
    cost += 0.25; 
    break; 
default: 
    cout << "wrong input!"; 
} 

请注意，您可以在switch声明

Answer 2

Case语句检查，看看输入值是否某个常数相匹配之前显示您的变量。

在您的情况下，您正在检查frameType的int值是1还是0，它与'1'的常数值相同。

此“1”（至极为char型）当与整数相比实际上将自动转换为一个整数，但它会转换为基于所述ascii table所以它将成为整数49的整数。

所以，当这一切编译它，如果你写了这样的事情：

switch (frameType) { 
case 49: 
    // Clearly frametype won't be 49 so this won't happen 
case 50: 
    // Same problem 

这些隐藏的转换可以给大家一个很大的痛苦，所以大多数的人会打开编译器警告，将停止编译如果这些“隐式转换”发生。

如果您编译时所有警告都打开并将它们视为错误，那么大多数编译器会为您抓住这类事情！在我工作的地方，这是编译的默认模式，因为我们都会犯这些错误......偶尔可以说。