Why does my std::getline() read blanks? Why do I need to press the enter key twice whenever I use std::getline() in VC++? How do I fix those problems?

faq116-5193

Posted: 10 Jun 04

Q: Why does my std::getline() read blanks?

A: Actually, your std::getline() does not read blanks. Instead, it reads the leftover delimiter (such as '\n' or ' ') from the previous input stream operation. Usually it happens when you use "cin>>buffer" followed by a call to "getline()".

Consider the following stream of data:

"I am so confused."

CODE

cin>>buffer_1;
getline(cin,buffer_2);

cin will read 'I' but it does not read the white space ' ' following 'I'. Thus, buffer_1 will store 'I' and buffer_2 will get the white space ' ' between 'I' and am. That's why you get blanks for your buffer_2.

Solution:
Use cin.ignore() to ignore the unwanted delimiter.

CODE

cin>>buffer_1; //buffer_1="I"
cin.ignore(1,' ');
getline(cin,buffer);//buffer_2="am so confused."

Q: Why do I need to press the enter key twice whenever I use std::getline() in VC++?

A: There is a bug in VC++'s implementation of string. This has been posted for quite sometimes by Microsoft at http://support.microsoft.com/default.aspx?scid=kb;en-us;240015 Thus, VC++'s std::getline() will read an extra character after encountering a delimiter.

Solution:
Go to your include folder (typically it can be found at C:\Program Files\Microsoft Visual Studio\VC98\Include) and edit STRING. NOTE that the file name is STRING and not STRING.H. Make the changes as mentioned in the article.

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