C++嵌套if语句

总是可以合法地嵌套if-else语句，这意味着可以在另一个if或else if语句中使用一个if或else if语句。

语法

嵌套if语句的语法如下所示：

if( boolean_expression 1) {
   // Executes when the boolean expression 1 is true
   if(boolean_expression 2) {
      // Executes when the boolean expression 2 is true
   }
}

您可以像嵌套if语句一样，以类似的方式嵌套else if...else。

示例

#include <iostream>
using namespace std;
 
int main () {
   // local variable declaration:
   int a = 100;
   int b = 200;
 
   // check the boolean condition
   if( a == 100 ) {
      // if condition is true then check the following
      if( b == 200 ) {
         // if condition is true then print the following
         cout << "Value of a is 100 and b is 200" << endl;
      }
   }
   cout << "Exact value of a is : " << a << endl;
   cout << "Exact value of b is : " << b << endl;
 
   return 0;
}

当以上代码编译并执行时，会产生以下结果：

Value of a is 100 and b is 200
Exact value of a is : 100
Exact value of b is : 200