diff --git a/Grade 9/Computer Science.md b/Grade 9/Computer Science.md new file mode 100644 index 0000000..356878f --- /dev/null +++ b/Grade 9/Computer Science.md @@ -0,0 +1,59 @@ +# Computer Science Review Sheet + +> ## Exam Layout +>> |Part|Description|Marks| +>> |:---|:----------|:----| +>> |```A```|**True / False**|10| +>> |```B```|**Multiple Choice**
- All java code learnt, selection, loops, methods, Arrays, methods, strings|38| +>> |```C```|**Short & Long Answers**
- Compare and contrast short code, methods, problem solving|20| +>> |```Total```||68| + +## Intro To Programming + +> ```Comments```: are used to explain and clarify program ocde for human reader + +> |Operator|Uses|Description| +> |:-------|:---|:----------| +> |+|a + b|Addition| +> |-|a- b|Subtraction| +> |*|a * b|Multiplication| +> |/|a / b|Division| +> |%|a % b|Mod, the Remainder| + +> **BEDMAS** rules still apply + +> ## Strings + +>> **```String:```** means a group of many characters +>> **```String Concatenation```**: means that two strings are combined into one using the "r" sign + +> ## Varaibles +>> Holder for data +>> We can use words instead of just a single letter +>> - can store more than just numbers +>> a place in memory (RAM: random access memory) where it can be stored or referred to +>> - Name, type, value + +>> To declare a variable +>> 1. Name +>> 2. Data Type + +>> A variable is the name of a reserved memory location +>> A varaible name is called an identifier +>> Reserved words cannot be used as an identifier + +> ## Java Primitives + +> Variables can be created for any of the data types listed +> The chart shows examples of how to create a new variable for each primitive + +> |Type|Range|Size|Variable|Declaration| +> |:---|:----|:---|:-------|:----------| +> |byte|-128 to 127|8 bits|bits_8|byte bits_8;| +> |short|-32768 to 32767|16 bits|TALL|short TALL;| +> |int|-2 billion to 2 billion|32-bits|sum|int sum;| +> |long|-9 quintillion to 9 quintillion(huge)|64 bits|mile|long mile;| +> |float|-3.4e+/-38 to 3.4e+/-38|32 bits|pi|float pi;| +> |double|-1.7e+/-308 to 1.7+/-308|64 bits|stuff|double stuff;| +> |char|Single (unicode) characters|16 bits|letter|char letter;| +