Change Values

Change Variable Values

If you assign a new value to an existing variable, the new value will replace the old one:

Example

int myNum = 15;  // myNum is 15
myNum = 10;  // Now myNum is 10

Note: This is normal and expected. Variables are meant to change while a program runs.

You can also assign the value of one variable to another:

Example

int myNum = 15;

int myOtherNum = 23;

// Assign the value of myOtherNum (23) to myNum
myNum = myOtherNum;

// myNum is now 23 (was 15)
printf("%d", myNum);

You can even copy values into variables that were declared earlier without a value:

Example

// Create a variable and assign a value
int myNum = 15;

// Declare a variable without assigning a value
int myOtherNum;

// Copy the value from myNum
myOtherNum = myNum;

// myOtherNum is now 15
printf("%d", myOtherNum);

Add Variables Together

You can use mathematical operators to work with variables.

For example, to add one variable to another, use the + operator:

Example

int x = 5;
int y = 6;
int sum = x + y;
printf("%d", sum);

You can also update a variable using its current value:

Example

int x = 5;
x = x + 1;
printf("%d", x);

Tip: Writing x = x + 1 means "take the current value of x and add 1 to it". Note: You will learn much more about operators in a later chapter.