“'x' 未在此范围内声明”的问题

Question

我试图编写一个简单的代码来尝试求解矩阵，但遇到了错误。很明显，我只是在做一些愚蠢的事情，所以我希望你能来救援！每当我运行代码并输入值时，它 returns 'x' 未在此范围内声明。有什么想法吗？

#include <iostream>
using namespace std;

int main() {

// Row 1
cout << "Please input the first row, first column (R1:C1)" << endl;
int R1C1;
cin >> R1C1;
cout << "Please input the first row, second column (R1:C2)" << endl;
int R1C2;
cin >> R1C2;
cout << "Please input the first row, third column (R1:C3)" << endl;
int R1C3;
cin >> R1C3;
cout << "Please input the first row, fourth column (R1:C4)" << endl;
int R1C4;
cin >> R1C4;

// Row 2
cout << "Please input the second row, first column (R2:C1)" << endl;
int R2C1;
cin >> R2C1;
cout << "Please input the second row, second column (R2:C2)" << endl;
int R2C2;
cin >> R2C2;
cout << "Please input the second row, third column (R2:C3)" << endl;
int R2C3;
cin >> R2C3;
cout << "Please input the second row, fourth column (R2:C4)" << endl;
int R2C4;
cin >> R2C4;

// Row 3
cout << "Please input the third row, first column (R3:C1)" << endl;
int R3C1;
cin >> R3C1;
cout << "Please input the third row, second column (R3:C2)" << endl;
int R3C2;
cin >> R3C2;
cout << "Please input the third row, third column (R3:C3)" << endl;
int R3C3;
cin >> R3C3;
cout << "Please input the third row, fourth column (R2:C4)" << endl;
int R3C4;
cin >> R3C4;

if (R1C1 > 1)
int x = R1C1 * (1/R1C1);
cout << x; 
return 0;
}

Answer 1

这里是

if (R1C1 > 1)
int x = R1C1 * (1/R1C1);
cout << x;

基本上是这个意思：

if (R1C1 > 1){
    int x = R1C1 * (1/R1C1);
}
cout << x;

如您所见，打印时 x 已不在范围内。它的范围仅限于 if 表达式的主体。为了减少混淆，人们通常会缩进 int x... 行，这样很明显它属于 if 语句并且与 cout 行不在同一范围内。

也许您想这样做：

if (R1C1 > 1){
    int x = R1C1 * (1/R1C1);
    cout << x;
}

“'x' 未在此范围内声明”的问题

Issues with "'x' was not declared in this scope"

c++

error-handling

declare