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4.5: Assignment Operator

  • Page ID
    10258
  • Discussion

    The assignment operator allows us to change the value of a modifiable data object (for beginning programmers this typically means a variable). It is associated with the concept of moving a value into the storage location (again usually a variable). Within C++ programming language the symbol used is the equal symbol. But bite your tongue, when you see the = symbol you need to start thinking: assignment. The assignment operator has two operands. The one to the left of the operator is usually an identifier name for a variable. The one to the right of the operator is a value.

    Simple Assignment
    
    int    age;    // variable set up
        then later in the program
    age = 21;
    

    The value 21 is moved to the memory location for the variable named: age. Another way to say it: age is assigned the value 21. 

    Assignment with an Expression
    
    int total_cousins;    // variable set up
        then late in the program
    total_cousins = 4 + 3 + 5 + 2;
    

    The item to the right of the assignment operator is an expression. The expression will be evaluated and the answer is 14. The value 14 would assigned to the variable named: total_cousins.

    Assignment with Identifier Names in the Expression
    
    int    students_period_1 = 25;    // variable set up with initialization
    int    students_period_2 = 19;
    int    total_students;
        then late in the program
    total_students = students_period_1 + students_period_2;
    

    The expression to the right of the assignment operator contains some identifier names. The program would fetch the values stored in those variables; add them together and get a value of 44; then assign the 44 to the total_students variable.

    Definitions

    assignment
    An operator that changes the value of a modifiable data object.