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C++ Data Types
course content

Зміст курсу

C++ Data Types

C++ Data Types

1. Introduction
OverviewArithmetic OperationsDivision int and doubleMath in C++Specifying a Type
2. Numerical Data Types
IntegersUsing IntegersType modifierFloatDoubleNumerical Data Types Summary
3. Text Data Type
CharStringIndexing a StringWorking With StringChanging The String PracticeFinding Text in a StringStrings in Memory
4. Other Data Types and Concepts
BooleanBoolean ExpressionsVoidAuto UnsignedImplicit Type ConversionExplicit Type Conversion

bookStrings in Memory

As shown in the video, strings have length and capacity. They can be accessed using .length() and .capacity() methods.

cpp

main

copy

              
12345678910111213

            
#include <iostream>

int main()
{
    std::string str = "String of 23 characters";
    std::cout << "String: " << str << std::endl;;
    std::cout << "Length:" << str.length() << " Capacity:" << str.capacity() << std::endl;

    str.append("...Now 32");

    std::cout << "---\nString: " << str << std::endl;;
    std::cout << "Length:" << str.length() << " Capacity:" << str.capacity() << std::endl;;
}

There are also two methods to work with capacity, .reserve(n) and shrink_to_fit().

  • .reserve(n) – set capacity to at least n;
  • .shrink_to_fit() – set capacity the same as the length.

So the .shrink_to_fit() is useful when you know you will not extend your string, but the capacity is greater than the length. And you can use .reserve(n) if your string is likely to be appended multiple times.

cpp

main

copy

              
12345678910111213

            
#include <iostream>

int main()
{
    std::string str = "String of 23 characters";
    std::cout << "Before reserve:\nLength:" << str.length() << " Capacity:" << str.capacity() << std::endl;
  
    str.reserve(60);
    std::cout << "After reserve:\nLength:" << str.length() << " Capacity:" << str.capacity() << std::endl;
  
    str.shrink_to_fit();  
    std::cout << "After shrink:\nLength:" << str.length() << " Capacity:" << str.capacity() << std::endl;
}

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