Break 语句不起作用
这个程序应该将 name 的字符数存储在变量 str_length 中（其中 name < 50 个字符以“.”结尾）我很困惑为什么这段代码只吐出第一个字符，这意味着它从循环中中断当 i = 0 时，对于诸如“Jonathan”之类的名字。难道它不应该解析字符串直到找到“.”，然后才从 for 循环中中断吗？
#include <iostream>
#include <cstring>
using namespace std;
int main()
{
string name;
int str_length;
cout << "What's your name" << endl;
cin >> name;
for (int i = 0; i < 50; i++)
{
cout << name[i];
if (name[i] == '.')
str_length = i;
break;
}
cout << endl;
system("PAUSE");
return 0;
}
This program should store the number of characters of name in the variable str_length (where name < 50 characters terminated by a ".") I'm baffled as to why this code only spits out the first character, meaning it breaks from the loop when i = 0, for a name such as "Jonathan." Shouldn't it parse through the string until it finds the ".", only then breaking from the for loop?
#include <iostream>
#include <cstring>
using namespace std;
int main()
{
string name;
int str_length;
cout << "What's your name" << endl;
cin >> name;
for (int i = 0; i < 50; i++)
{
cout << name[i];
if (name[i] == '.')
str_length = i;
break;
}
cout << endl;
system("PAUSE");
return 0;
}
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评论（3）
你有：
这实际上是：
你想要：
你在每个循环结束时
breaking。You have:
Which is actually:
You want:
You are
breaking at the end of each loop.您在
if条件周围缺少{}。所以break是在没有任何条件的情况下执行的，因此循环在第一次迭代时退出。You are missing
{}aroundifcondition. Sobreakis executed without any condition, hence the loop is exited in the first iteration itself.这表明即使对于一行 if 语句也不使用大括号也是危险的。我怀疑你这样做了：
然后添加了
break。如果你这样做了：在前面，在花括号内添加中断是很自然的，并且你不会遇到这个错误。
This demonstrates the danger of not using braces even for one line if statements. I suspect you did this:
and then added the
breaklater. If you had done this:up front, it would have been natural to add the break inside the curly braces, and you wouldn't have had the bug.