The most popular library is almost certainly the string library, with perhaps the function strlen() called most often. strlen() returns ...
The most popular library is almost certainly the string library, with perhaps the function strlen() called most often. strlen() returns the length of a null-terminated string. Listing 21.1 illustrates its use.
Listing 21.1. strlen().
1: #include <iostream.h>
2: #include <string.h>
3:
4: int main()
5: {
6: char buffer80];
7: do
8: {
9: cout << "Enter a string up to 80 characters: ";
10: cin.getline(buffer,80);
11: cout << "Your string is " << strlen(buffer);
12: cout << " characters long." << endl;
13: } while (strlen(buffer));
14: cout << "\nDone." << endl;
15: return 0;
16: }
Output: Enter a string up to 80 characters: This sentence has 31 characters
Your string is 31 characters long.
Enter a string up to 80 characters: This sentence no verb
Your string is 21 characters long.
Enter a string up to 80 characters:
Your string is 0 characters long.
Done.
Analysis: On line 6, a character buffer is created, and on line 9 the user is prompted to enter a string. As long as the user enters a string, the length of the string is reported on line 11.
Note the test in the do...while() statement: while (strlen(buffer)). Since strlen() will return 0 when the buffer is empty, and since 0 evaluates FALSE, this while loop will continue as long as there are any characters in the buffer.
Goto String Standard Library to get all the String functions
