三道C++题，高手大神多谢了

Question

1. read the program and give the running result

#include <string>
#include <iostream>
using namespace std;
int main()
{
string a("abc");//创建字符串a
string b("StringB");
cout <<"Length of a=" <<a.length() <<endl;//此时a 的长度为3
cout <<a <<endl;//字符串a 的内容为“abc”
a.append("EFG");//在字符串末尾添加“EFG”
cout <<"Length of a=" <<a.length() <<endl;//此时字符串长度为6
cout <<a <<endl;//字符串a 的内容为“abcEFG”
a.insert(3,b);//在字符串a 的第三个字符后插入字符串b
cout <<a <<endl;//字符串a 的内容为“abcStringBEFG”
cout <<a.compare("ABCDEFG") <<endl;//字符串a 与“ABCDEFG”比较，不同应输出1
cout <<a.compare(a) <<endl;//字符串a 与自己比较，相同应输出0
cout <<a.empty() <<endl;//字符串a 不是空的，应输出0
a.swap(b);//字符串a 和b 内容交换
cout <<"String a is "<<a <<endl <<"String b is "<<b <<endl;
return 0;
}

2. read the program and give the running result

#include<iostream>
using namespace std;

int main()
{
int sum = 0;
for(int i=1; i<=100;i++)
{
if(i>50)
break;
if(i%3==0)
continue;
sum += i;
}
cout << sum << endl;
return 0;
}

3. Write a program that contains four arrays. Three of the arrays should contain your first name, middle initial, and last name. Use the string-copying function to copy these strings together into the fourth array, full name.

Answer 1

第一题：
Length of a=3
abc
Length of a=6
abcEFG
abcStringBEFG
1
0
0
String a is StringB
String b is abcStringBEFG
请按任意键继续. . .
第二题：
867
请按任意键继续. . .
第三题：
#include<iostream>
#define MAX 20
using namespace std;

int main()
{
char s1[MAX], s2[MAX], s3[MAX];
char s[60];
cin>>s1;
cin>>s2;
cin>>s3;
int i, j, k, l;
for(i = 0; s1[i]; i ++){
s[i] = s1[i];
k = i;
}
for(i = 0, j = k + 1; s2[i]; i ++, j ++){
s[j] = s2[i];
l = j;
}
for(i = 0, j = l + 1; s3[i]; i ++, j ++){
s[j] = s3[i];
}
i = 0;
while(i != j){
cout<<s[i++];
}
return 0;
}

Answer 2

1.
Length of a=3
abc
Length of a=6
abcEFG
abcStringBEFG
1
0
0
String a is StringB
String b is abcStringBEFG

2.
867

3.
#include<iostream>
#include<string>
using namespace std;

int main()
{
string firName("Rober");
string midName("none");
string lasName("Domalski");
string fullName;
fullName+=(firName+" "+midName+" "+lasName);
cout<<fullName;

}