7 min read•Last Updated on June 18, 2024
Avanish Gupta
user_sophia9212
Avanish Gupta
user_sophia9212
Sometimes, you will encounter situations where you need to perform the following operation:
int integerOne = 6;
integerOne = integerOne * 2;
This is a bit clunky with the repetition of integerOne in line two. We can condense this with this statement:
integerOne *= 2;
The "*= 2" is an example of a compound assignment operator, which multiplies the current value of integerOne by 2 and sets that as the new value of integerOne. Other arithmetic operators also have compound assignment operators as well, with addition, subtraction, division, and modulo having +=, -=, /=, and %=, respectively.
There are special operators for the two following operations in the following snippet well:
integerOne += 1;
integerTwo -= 1;
These can be replaced with a pre-increment/pre-decrement (++i or - -i) or post-increment/post-decrement (i++ or i- -) operator. You only need to know the post-variant in this course, but it is useful to know the difference between the two. Here is an example demonstrating the difference between them:
int integerOne = 2;
integerOne++;
System.out.println(integerOne);
++integerOne;
System.out.println(integerOne);
System.out.println(integerOne++);
System.out.println(++integerOne);
3
4
4
6
By itself, there is no difference between the pre-increment and post-increment operators, but it's evident when you use it in a method such as the println method. For this statement, I will write a debugging output, which happens when we trace the code, which means to follow it line-by-line.
Value of integerOne after line 1: 2
Value of integerOne after line 2: 3
Value of integerOne after line 3: 3
Value of integerOne after line 4: 4
Value of integerOne after line 5: 4
Value of integerOne before printing on line 6: 4
Value of integerOne after line 6: 5 (post-increment increments after the method)
Value of integerOne before printing on line 7: 6
Value of integerOne after line 7: 6 (pre-increment increments before the method)
Now that you’ve learned about code tracing, let’s do some practice! You can use trace tables like the ones shown below to keep track of the values of your variables as they change.
x | y | z | output |
| x | | | --- | --- | | y | | | z | | | output | |
Here are some practice problems that you can use to practice code tracing. Feel free to use whichever method you’re the most comfortable with!
Trace through the following code:
int a = 6;
int b = 4;
int c = 0;
a *= 3;
b -= 2;
c = a % b;
a += c;
b = a - b;
c *= b;
Answer:
Note: Your answers could look different depending on how you’re tracking your code tracing.
double x = 15.0;
double y = 4.0;
double z = 0;
x /= y;
y *= x;
z = y % x;
x += z;
y = x / z;
z *= y;
Answer:
int a = 100;
int b = 50;
int c = 25;
a -= b;
b *= 2;
c %= 4;
a = b + c;
b = c - a;
c = a * b;
Answer:
int a = 5;
int b = 3;
int c = 0;
a *= 2;
b -= 1;
c = a % b;
a += c;
b = a - b;
c *= b;
Answer:
int x = 5;
int y = 10;
int z = 15;
x *= 2;
y /= 3;
z -= x;
x = y + z;
y = z - x;
z = x * y;
Answer:
double x = 10;
double y = 3;
double z = 0;
x /= y;
y *= x;
z = y - x;
x += z;
y = x / z;
z *= y;
Answer:
Code tracing is the process of manually following the execution of a program to understand how it works and identify any errors or bugs. It involves stepping through each line of code, keeping track of variable values and function calls.
Term 1 of 5
Code tracing is the process of manually following the execution of a program to understand how it works and identify any errors or bugs. It involves stepping through each line of code, keeping track of variable values and function calls.
Term 1 of 5
Code tracing is the process of manually following the execution of a program to understand how it works and identify any errors or bugs. It involves stepping through each line of code, keeping track of variable values and function calls.
Term 1 of 5
Compound assignment operators are shorthand notations that combine an arithmetic operation with the assignment operator. They allow you to perform an operation and assign the result to a variable in a single step.
+= operator: This operator adds the value on the right side of it to the variable on the left side, and then assigns the result back to that variable.
-= operator: This operator subtracts the value on the right side of it from the variable on the left side, and then assigns the result back to that variable.
*= operator: This operator multiplies the value on the right side of it with the variable on the left side, and then assigns the result back to that variable.
Pre-increment is an operator that increases the value of a variable before using it in an expression. It adds one unit to the original value and then returns the updated result.
Decrementing: Decrementing refers to decreasing the value of a variable by subtracting some quantity from it.
Post-increment: Post-increment is another type of incrementation where we increase the value after using it in an expression.
Incrementing: Incrementing is the general term for increasing the value of a variable, whether it's done before or after using it in an expression.
Post-increment is an operator that increases the value of a variable after using it in an expression. It returns the original value and then adds one unit to it.
Decrementing: Decrementing refers to decreasing the value of a variable by subtracting some quantity from it.
Pre-increment: Pre-increment is another type of incrementation where we increase the value before using it in an expression.
Incrementing: Incrementing is the general term for increasing the value of a variable, whether it's done before or after using it in an expression.
Code tracing is the process of manually following the execution of a program to understand how it works and identify any errors or bugs. It involves stepping through each line of code, keeping track of variable values and function calls.
Debugging: The process of finding and fixing errors or bugs in a program.
Variable Scope: Refers to where in a program a variable can be accessed and used.
Function Call: Invoking or using a function in your code to perform a specific task.