C++ Standard Library Strings
Our early (pre-Qt) examples will make use of C++ Standard Library strings (see Appendix B). Standard Library strings have many disadvantages when compared to QStrings, but they are easy to use and have a similar public interface that includes many functions to construct and modify strings.
Example 1.14 demonstrates its basic usage.
Example 1.14. src/generic/stlstringdemo.cpp
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#include #include int main() { using namespace std; string s1("This "), s2("is a "), s3("string."); s1 += s2; <-- 1 string s4 = s1 + s3; cout << s4 << endl; string s5("The length of that string is: "); cout << s5 << s4.length << " characters." << endl; cout << "Enter a sentence: " << endl; getline(cin, s2); cout << "Here is your sentence: " << s2 << endl; cout << "The length of it was: " << s2.length() << endl; return 0; } (1)concatenation |
Here is the compile and run:
src/generic> g++ -ansi -pedantic -Wall stlstringdemo.cpp src/generic> ./a.out This is a string. The length of that string is 17 Enter a sentence: 20 years hard labour Here is your sentence: 20 years hard labour The length of it was: 20 src/generic>
Observe that we used the getline(istream, string) function to take a string from standard input stream. We will learn more about input from streams in the following section.
Streams
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