抛出 an exception
抛出错误，使用try throw catch 捕捉
定义一个Exception类
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| class BadLengthException{// 这是一个exception类
public:
int length;
BadLengthException(int n){
this->length = n; //参数初始化
}
int what() const;//创建一个what方法，后面加const表明该函数权限是只读，无法改变成员变量的值
};
int BadLengthException::what() const{
return length;
}
|
使用try->throw->catch
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| bool checkUsername(string username) {
bool isValid = true;
int n = username.length();
if(n < 5) {
throw BadLengthException(n);//抛出异常
}
for(int i = 0; i < n-1; i++) {
if(username[i] == 'w' && username[i+1] == 'w') {
isValid = false;
}
}
return isValid;
}
try {
bool isValid = checkUsername(username);
if(isValid) {
cout << "Valid" << '\n';
} else {
cout << "Invalid" << '\n';
}
} catch (BadLengthException e) {
cout << "Too short: " << e.what() << '\n';
}
|
