, NOTES
WHAT IS C
DATA TYPES AND VARIABLES
WHAT IS C? (THE FOUNDATION)
C IS A PROCEDURAL, LOW-LEVEL LANGUAGE CREATED BY DENNIS RITCHIE IN 1972. IT'S FAST, EFFICIENT, AND
THE "MOTHER" OF LANGUAGES LIKE C++, JAVA, AND PYTHON. WHY LEARN C?
BUILDS STRONG BASICS FOR ANY PROGRAMMING.
USED IN OS (LINUX), GAMES, EMBEDDED SYSTEMS.
EXAM FAVORITE—FOCUS ON SYNTAX, LOGIC, AND MEMORY.
BASIC PROGRAM SKELETON:
BREAKDOWN:
→
1.HEADER FILES #INCLUDE <STDIO.H>
→
2.MAIN FUNCTION INT MAIN()
→
3.BODY { ... } (WHERE LOGIC IS WRITTEN)
→
4.RETURN STATEMENT ENDS PROGRAM
EXECUTION
QUICK TIP: EVERY PROGRAM NEEDS #INCLUDE, MAIN(), AND
RETURN 0;.
DATA TYPES & VARIABLES (STORING DATA)
DATA TYPES SPECIFY THE TYPE OF DATA A VARIABLE CAN STORE AND HOW MUCH MEMORY IT WILL OCCUPY.
1. BASIC (PRIMITIVE) DATA TYPES
THESE ARE THE FUNDAMENTAL TYPES USED TO STORE SIMPLE VALUES.
INT – USED TO STORE INTEGERS (WHOLE NUMBERS).
FLOAT – USED TO STORE DECIMAL NUMBERS.
DOUBLE – USED TO STORE LARGE DECIMAL NUMBERS WITH HIGHER PRECISION.
CHAR- USED TO STORE A SINGLE CHARACTER.
VOID – REPRESENTS NO DATA TYPE (USED IN FUNCTIONS THAT RETURN NOTHING).
2. DERIVED DATA TYPES
DERIVED FROM THE BASIC DATA TYPES.
ARRAY – STORES MULTIPLE VALUES OF THE SAME TYPE.
POINTER – STORES THE ADDRESS OF ANOTHER VARIABLE.
STRUCTURE – STORES A COLLECTION OF DIFFERENT DATA TYPES.
UNION – SIMILAR TO STRUCTURE BUT SHARES THE SAME MEMORY SPACE.
FUNCTION – A BLOCK OF CODE THAT PERFORMS A SPECIFIC TASK AND MAY RETURN A VALUE.
3. USER-DEFINED DATA TYPES
DEFINED BY THE USER FOR BETTER CODE READABILITY AND FLEXIBILITY.
TYPEDEF – GIVES A NEW NAME TO AN EXISTING DATA TYPE.
ENUM – USED TO ASSIGN NAMES TO INTEGER CONSTANTS, IMPROVING CLARITY.
WHAT IS C
DATA TYPES AND VARIABLES
WHAT IS C? (THE FOUNDATION)
C IS A PROCEDURAL, LOW-LEVEL LANGUAGE CREATED BY DENNIS RITCHIE IN 1972. IT'S FAST, EFFICIENT, AND
THE "MOTHER" OF LANGUAGES LIKE C++, JAVA, AND PYTHON. WHY LEARN C?
BUILDS STRONG BASICS FOR ANY PROGRAMMING.
USED IN OS (LINUX), GAMES, EMBEDDED SYSTEMS.
EXAM FAVORITE—FOCUS ON SYNTAX, LOGIC, AND MEMORY.
BASIC PROGRAM SKELETON:
BREAKDOWN:
→
1.HEADER FILES #INCLUDE <STDIO.H>
→
2.MAIN FUNCTION INT MAIN()
→
3.BODY { ... } (WHERE LOGIC IS WRITTEN)
→
4.RETURN STATEMENT ENDS PROGRAM
EXECUTION
QUICK TIP: EVERY PROGRAM NEEDS #INCLUDE, MAIN(), AND
RETURN 0;.
DATA TYPES & VARIABLES (STORING DATA)
DATA TYPES SPECIFY THE TYPE OF DATA A VARIABLE CAN STORE AND HOW MUCH MEMORY IT WILL OCCUPY.
1. BASIC (PRIMITIVE) DATA TYPES
THESE ARE THE FUNDAMENTAL TYPES USED TO STORE SIMPLE VALUES.
INT – USED TO STORE INTEGERS (WHOLE NUMBERS).
FLOAT – USED TO STORE DECIMAL NUMBERS.
DOUBLE – USED TO STORE LARGE DECIMAL NUMBERS WITH HIGHER PRECISION.
CHAR- USED TO STORE A SINGLE CHARACTER.
VOID – REPRESENTS NO DATA TYPE (USED IN FUNCTIONS THAT RETURN NOTHING).
2. DERIVED DATA TYPES
DERIVED FROM THE BASIC DATA TYPES.
ARRAY – STORES MULTIPLE VALUES OF THE SAME TYPE.
POINTER – STORES THE ADDRESS OF ANOTHER VARIABLE.
STRUCTURE – STORES A COLLECTION OF DIFFERENT DATA TYPES.
UNION – SIMILAR TO STRUCTURE BUT SHARES THE SAME MEMORY SPACE.
FUNCTION – A BLOCK OF CODE THAT PERFORMS A SPECIFIC TASK AND MAY RETURN A VALUE.
3. USER-DEFINED DATA TYPES
DEFINED BY THE USER FOR BETTER CODE READABILITY AND FLEXIBILITY.
TYPEDEF – GIVES A NEW NAME TO AN EXISTING DATA TYPE.
ENUM – USED TO ASSIGN NAMES TO INTEGER CONSTANTS, IMPROVING CLARITY.
