c++输入一句话输出每个字母出现的个数

#include<iostream>
#include<string>
#include<vector>
using namespace std;
void main()
{
char sentence[100];
cout<<"Input a sentence:"<<endl;
gets(sentence);
vector<int>num;
vector<char>alp;
alp.push_back(sentence[0]);
num.push_back(1);
for(int i=1,count,temp=0;i<strlen(sentence);i++)
{
count=alp.size();
for(int k=0;k<alp.size();k++)
{
if(sentence[i]!=alp[k])
{
count--;
}
else
num[k]++;
}
if(count==0)
{
alp.push_back(sentence[i]);
num.push_back(1);
}


}
for(int i=0;i<alp.size();i++)
cout<<alp[i]<<" "<<num[i]<<endl;

}