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📜  C++ if-else

📅  最后修改于: 2020-10-16 06:24:23             🧑  作者: Mango

C++ if-else

在C++编程中，if语句用于测试条件。 C++中有多种类型的if语句。

  • IF声明
  • if-else语句
  • 嵌套if语句
  • if-else-if梯子

C++ IF语句

C++ if语句测试条件。条件为真时执行。

if(condition){  
//code to be executed  
}

C++ IF示例

#include 
using namespace std;
 
int main () {
   int num = 10;  
            if (num % 2 == 0)  
            {  
                cout<<"It is even number";  
            } 
   return 0;
}

输出：/ p>

It is even number

C++ IF-else语句

C++ if-else语句也测试条件。如果条件为true则执行block，否则执行block。

if(condition){  
//code if condition is true  
}else{  
//code if condition is false  
}

C++ If-else示例

#include 
using namespace std;
int main () {
   int num = 11;  
            if (num % 2 == 0)  
            {  
                cout<<"It is even number";  
            } 
            else
            {  
                cout<<"It is odd number";  
            }
   return 0;
}

输出：

It is odd number

C++ If-else示例：用户输入

#include 
using namespace std;
int main () {
    int num;
    cout<<"Enter a Number: ";
    cin>>num;
            if (num % 2 == 0)  
            {  
                cout<<"It is even number"<

输出：

Enter a number:11
It is odd number

输出：

Enter a number:12
It is even number

C++ IF-else-if梯形图语句

C++ if-else-if阶梯语句从多个语句执行一个条件。

if(condition1){  
//code to be executed if condition1 is true  
}else if(condition2){  
//code to be executed if condition2 is true  
}  
else if(condition3){  
//code to be executed if condition3 is true  
}  
...  
else{  
//code to be executed if all the conditions are false  
}

C++ If else-if示例

#include 
using namespace std;
int main () {
       int num;
       cout<<"Enter a number to check grade:";  
       cin>>num;
            if (num <0 || num >100)  
            {  
                cout<<"wrong number";  
            }  
            else if(num >= 0 && num < 50){  
                cout<<"Fail";  
            }  
            else if (num >= 50 && num < 60)  
            {  
                cout<<"D Grade";  
            }  
            else if (num >= 60 && num < 70)  
            {  
                cout<<"C Grade";  
            }  
            else if (num >= 70 && num < 80)  
            {  
                cout<<"B Grade";  
            }  
            else if (num >= 80 && num < 90)  
            {  
                cout<<"A Grade";  
            }  
            else if (num >= 90 && num <= 100)  
            {  
                cout<<"A+ Grade";
            }  
    }

输出：

Enter a number to check grade:66
C Grade

输出：

Enter a number to check grade:-2
wrong number