C++ Examples

Strings

#include <algorithm>
#include <iostream>
#include <string>

using namespace std;

string toLower(string);
string toUpper(string);

int main() {
    string str = "Hello";

    cout << "string: " << str << endl;
    cout << "tolower: " << toLower(str) << endl;
    cout << "toupper: " << toUpper(str) << endl;
    cout << "string.find('e'): " << str.find('e') << endl;
    cout << "string.length(): " << str.length() << endl;
    cout << "string.replace(0, 1, \"j\"): " << str.replace(0, 1, "j") << endl;
    cout << "string.substr(2, 2): " << str.substr(2, 2) << endl;

    string name = "Bob";
    double value = 123.456;
    cout << name << " earned $" << fixed << setprecision (2) << value << endl;

}

string toLower(string str) {
    transform(str.begin(), str.end(), str.begin(), ::tolower);

    return str;
}

string toUpper(string str) {
    transform(str.begin(), str.end(), str.begin(), ::toupper);

    return str;
}

Output

string: Hello
tolower: hello
toupper: HELLO
string.find('e'): 1
string.length(): 5
string.replace(0, 1, "j"): jello
string.substr(2, 2): ll
Bob earned $123.46

Files

// This program demonstrates reading a text file with error handling.

// References:
//     https://en.wikibooks.org/wiki/C%2B%2B_Programming

#include <fstream>
#include <iostream>
#include <string>

using namespace std;

void readFile(string);

int main() {
    string FILENAME = "temperature.txt";

    readFile(FILENAME);
}

void readFile(string filename)
{
    fstream file;
    string line;

    file.open(filename, fstream::in);
    if (file.is_open()) {
        while (getline(file, line))
        {
            cout << line << endl;
        }
        file.close();
    } else {
        cout << "Error reading " << filename << endl;
    }
}

Output

Celsius,Fahrenheit
0,32
10,50
20,68
...
80,176
90,194
100,212

References

• Wikiversity: Computer Programming