奇怪的行为

Question

I compiled on Ubuntu a program that was developed for (and works on) Windows. On Ubuntu, I see this code:

string s = values_[9];
cout << s << endl;
cout << s << "x\n";

producing this output:

high
xigh

The expected output for the second line is "highx". I know that the value of values_[9] is originally read from a file (written on Windows). Printing other strings seems to work normally.

What's going on here?

Answer 1

Run the command with its output piped through cat -A . Probably either the value of s , or the output produced by endl is giving you a '\r' character, which typically sends the cursor back to the beginning of the line.

EDIT: On further thought, the stray '\r' is almost certainly in s , not in the output produced by endl . I had thought there might be some funny locale stuff going on, but having s equal to "high\r" explains the symptoms.

EDIT2: If your system doesn't have cat -A (it's a GNU extension), try cat -v or, if you're desperate, od -c .

Answer 2

The string you're printing has a carriage return '\r' in it. What's happening is that you're printing high , then the carriage return, which puts the cursor back on the start of the line. Then, when you print the x , it overwrites the first letter on the line.

You should either remove the carriage return from the source file (eg with dos2unix(1) or many other options), or change your code to strip the carriage return after reading the file in.

Answer 3

What is probably happening, is that there is a \r in values_[9] .