C++ Primer Plus

Program Notes

The program in Listing 8.9 uses new to create a new string for holding the selected characters. One awkward possibility is that an uncooperative user may request a negative number of characters. In that case, the function sets the character count to 0 and eventually returns the null string. Another awkward possibility is that an irresponsible user may request more characters than the string contains. The function protects against this by using a combined test:

i < n && str[i]

The i < n test stops the loop after n characters have been copied. The second part of the test, the expression str[i], is the code for the character about to be copied. If the loop reaches the null character, the code is 0, and the loop terminates. The final ...