题解 | #计算某字母出现次数#

1.输入
vector<char>装字符串
char c_look装查找字符</char>

2.
关键是大小写区分
定义b_look
当字符在az之间，b_look = c_look-32；
当字符在AZ之间，b_look= c_look+32；
否则b_look= c_look；

3.代码
#include<iostream>
#include<string>
#include<vector>
#include <algorithm>
using namespace std;</algorithm></vector></string></iostream>

int main()
{
vector<char> str;
char c_look;
char tem;
int i;
for(i = 0;;i++)
{
tem = getchar();
if(tem == '\n')
break;
else
str.push_back(tem);
}
c_look = getchar();
char b_look;
if((c_look<='Z'&&c_look>='A'))
{
b_look = c_look+32;
}
else if((c_look<='z'&&c_look>='a'))
{
b_look = c_look-32;
}
else
b_look = c_look;
int sum = 0;
for(int k = 0;k<i+1;k++)
{
tem = str.back();
str.pop_back();
if(tem == c_look||tem == b_look)
++sum;
}
cout<<sum<<endl;
}</char>