About CIN, scanf and getline, getchar, CIN Mixed use of getline

When they are mixed, sometimes it is impossible to enter a string or there are more spaces in the string

Here's why ：

cin and scanf Or leave a space after the input buffer is completed \n( See what you end with when you type )

And the next one cin and scanf Will directly ignore the remaining space or \n, Read in your new input

however getline,getchar,cin.getline It doesn't ignore this space or \n, They'll read this into

If cin perhaps scanf What's left is a space , Then use getline,getchar,cin.getline The input string will be preceded by one more space

If cin perhaps scanf What's left is \n, Then use getline,getchar,cin.getline Will read the \n And think you entered \n So as to directly end the input

resolvent ：

After use cin and scanf after , add a sentence getchar() Eat the remaining spaces or \n, And then use getline,getchar,cin.getline

Be careful ：

1.cout and printf It doesn't affect

2.getline,getchar,cin.getline There will be no spaces or \n