#include<iostream>
using namespace std;
int main(){
     char c;//定义
     cin>>c;//输入
     cout<<(int) c;//强制类型转换并输出
     return 0;
}

强制转成int并输出即可

#include <cstdio>
using namespace std;
int main(){
    char n;
    scanf("%c", &n);
    printf("%d", n);
    return 0;
}

#include<iostream>
using namespace std;
int main(){
	char a;
	cin >> a;
	cout << int(a);
	return 0;
}

最短代码

#include<bits/stdc++.h>
using namespace std;
int main(){
	char s;cin>>s;
	cout<<int(s);
	return 0;
} 

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int a;
    char b;
    cin>>b;
    a=int(b);
    cout<<a;
    return 0;   
}

#include<iostream>
using namespace std;
long long q,w,e,r,t,y,u,i,o,p,d,f,g,h,j,k,l,z,x,c,v,b,n,m;
string s;
long long a[100000],as[100000],asd[100000];
char cc;
int main()
{
	cin>>cc;cout<<cc+0;
    return 0;
}

#include <iostream>
using namespace std;
int main()
{
    char a;
    cin>>a;
    cout<<(int)a<<endl;
    return 0;
}

#include<iostream>
using namespace std;
long long q,w,e,r,t,y,u,i,o,p,d,f,g,h,j,k,l,z,x,c,v,b,n,m;
string s;
long long a[100000],as[100000],asd[100000];
char cc;
int main()
{
	cin>>cc;cout<<cc+0;
    return 0;
}