C++ Getline忽略输入的第一个字符
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Getline ignoring first character of input
提问by lisovaccaro
I'm just starting with arrays in C++ and I'm having a problem getting the first character of an array.
我刚开始使用 C++ 中的数组，但在获取数组的第一个字符时遇到了问题。
This is my code,
这是我的代码
1- I enter a name, such as "Jim"
1- 我输入一个名字，例如“Jim”
char name[30];
cin.ignore();
cin.getline(name, 30);
2- Right away I try to cout the array
2-我立即尝试计算数组
cout<<"NAME:"<<name; // THIS PRINTS 'im'
I was sure it would print 'J'. What am I doing wrong?
我确信它会打印“J”。我究竟做错了什么？
回答by Amit
Here is signature of cin.ignore:
这是cin.ignore的签名：
istream& ignore (streamsize n = 1, int delim = EOF);
So if you call ignore function without any parameters, it will ignore '1' char by default from input. In this case it ignored 'J'. Remove ignore call and you will get 'Jim'.
因此，如果您在不带任何参数的情况下调用 ignore 函数，默认情况下它会从输入中忽略 '1' 字符。在这种情况下，它忽略了“J”。删除忽略电话，你会得到“吉姆”。
回答by someone
Just remove cin.ignore();
只需删除 cin.ignore();
This ignores the first character, thus you miss the 'J'.
这会忽略第一个字符，因此您会错过 'J'。
回答by gengiskanhg
I had this piece of code with the problem that it was eating the first character after the first cycle (first cycle was ok)
我有这段代码的问题是它在第一个周期后吃掉了第一个字符（第一个周期没问题）
do{
cout << endl << "command:> ";
string cmdStr1="";
cin.ignore();
getline(cin, cmdStr1);
cout << "cin= " << cmdStr1 << endl; //For Debuging
//...more code here
}while(1);
Output was:
输出是：
command:> pos
命令：> pos
cin= pos
cin= pos
command:> pos ... from 2nd loop it started to delete the 1st character
命令：> pos ... 从第二个循环开始删除第一个字符
cin= os
cin= os
...
...
If "cin.ignore();" was commented then it resulted in a "segmentation fault":
如果“cin.ignore();” 被评论然后它导致了“分段错误”：
command:> cin=
命令：> cin=
Segmentation fault
分段故障
Solution working for me:
对我有用的解决方案：
To move the "cin.ignore();" line just before the do-while loop.
移动“cin.ignore();” 在 do-while 循环之前的行。
cin.ignore();
do{
std::cout << endl << "command:> ";
std::string cmdStr1="";
std::getline(std::cin, cmdStr1);
std::cout << "cin= " << cmdStr1 << endl; //For Debuging
//...more code here
}while(1);
Output was:
输出是：
command:> pos
命令：> pos
cin= pos
cin= pos
command:> pos
命令：> pos
cin= pos
cin= pos
...
...
...
...
P.S. It was incredible hard to put code here... I am disappointment to continue collaborating.
PS 把代码放在这里真是太难了……我对继续合作感到失望。
