本文更新日志:
1)20180412,第1版:判断一个字符是否为数字或字母、闰年、保留指定的小数位数;
2)
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C++中,如何判断一个字符是数字或者字母:
// 判断ch是数字,条件是 (ch>='0' && ch<='9')
// 判断ch是字符,条件是 (ch>='A' && ch<='Z' || ch>='a' && ch<='z')
void transfer_01(){
bool is_digit, is_letter;
for(int i=0; i<len; i++){
is_digit = (source[i]>='0' && source[i]<='9');
is_letter = (source[i]>='A' && source[i]<='Z') || (source[i]>='a' && source[i]<='z');
if(is_digit || is_letter){
source[i] = '1';
}else{
source[i] = '0';
}
}
}
闰年:
#include<iostream>
using namespace std;
int main()
{
int year;
bool case1, case2;
while(cin>>year)
{
case1 = (year%4==0 && year%100!=0);
case2 = (year%400==0);
if(case1 || case2)
cout<<year<<" is leap year."<<endl;
else
cout<<year<<" is not leap year."<<endl;
cout<<"========"<<endl;
}
return 0;
}
保留几位小数:
ratio = 66.666667
// way-1
#include <iomanip>
cout<<setiosflags(ios::fixed);
cout.precision(2);
cout<<ratio<<endl;
// way-2
#include <stdio.h>
printf("%.2f", ratio);