20191117-STD::讲解及求平均数例题
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#include "stdafx.h"
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#include "cstdio"
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#include "iostream"
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#include "algorithm"
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using namespace std;
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int main()
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{
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char grade='A';
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switch(grade)
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{
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case 'A': cout<<"85~100\n";break;
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case 'B': cout<<"70~84\n";break;
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case 'C': cout<<"60~69\n";break;
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case 'D': cout<<"<60\n";break;
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default: cout<<"error\n";break;
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}
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}
注释掉using namespace std;,代码如下:
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#include "stdafx.h"
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#include "cstdio"
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#include "iostream"
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#include "algorithm"
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//using namespace std;
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int main()
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{
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char grade='A';
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switch(grade)
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{
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case 'A': std::cout<<"85~100\n";break;
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case 'B': std:: cout<<"70~84\n";break;
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case 'C': std:: cout<<"60~69\n";break;
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case 'D': std:: cout<<"<60\n";break;
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default: std:: cout<<"error\n";break;
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}
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}
解题思路：
如果不加using namespace std;,则cout等命令前需加上std::,如上例,注释掉了using namespace std;,下面的代码做了相应修改.
下一题,题目:
随机输入三个带小数的数,求平均值:
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#include "stdafx.h"
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#include "cstdio"
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#include "iostream"
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#include "algorithm"
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using namespace std;
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int main()
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{ float a,b,c;
cin>>a>>b>>c; -
cout<<(a+b+c)/3;
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}
解题思路:因为是带小数的题,所以用到了FLOAT,求平均数即:(a+b+c)/3
