This document provides an overview of the C programming language. It discusses that C is a popular system programming language developed for UNIX, and is similar to assembly. It describes the main components of a C program, including functions, variables, data types, and control statements. It also explains some key C concepts like tokens, keywords, data types, storage specifiers, and the build process that compiles C source code into an executable program.
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Overview
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Most popular system programming language
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Developed for UNIX. Linux & MySQL are written in C
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Nearest to Assembly
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Install Eclipse IDE from Embedkari Toolbox
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Text Editor,Compiler,Assemblet,Linker and Debugge
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Programming Language
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Program is a set of pre-defined instructions to a device/cpu
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Lets take an example of normal language we use for communicatiion
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Mr A ask a fast food person Mr B
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Give me “one large Pizza”
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Here Give Me is instruction and rest is data
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The data itself has three parts
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Quantity , Size , Item description
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Mr B has to decode both instruction and data elements, Then act
accordingly. Mr B may also check payment status
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Mr B is already trained to do the required action
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Now one can replace Mr B with a ML trained Robot OR A pre-
programmed Vending machine
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There may be another customer Mr C with different order and item
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Program Components
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Group of instructions working on data
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Functions
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Data can be constant or variable at run time
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Variables
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Different kind of data like numbers, characters,strings
etc
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Data Type
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Different actions are possible based on the conditions
set for input data
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Control statements & Expressions
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Token
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Token is the smallest element of C program for Compiler
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Keywords
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Identifiers
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Constants
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Strings
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Special Symbols
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Operators
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Keywords are pre-defined or reserved words
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Keywords-32
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Primitive Data Types and related Keywords (8)
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int long double float short char unsigned signed
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Custom Data Types Related (3)
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struct enum typedef
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Control statements (12)
goto if else do while for
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return switch case break continue default
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Storage specifiers(4)
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auto register static extern
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Type Qualifiers(2) const volatile
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Misc(3) : void sizeof union
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Note: There are some additional reserve words added C99 onwards
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Data Type size @ARM ABI
C Type Machine Type Size
char unsigned byte 1
unsigned char unsigned byte 1
signed char signed byte 1
[signed]short signed halfword 2
unsigned short unsigned halfword 2
[signed] int signed word 4
unsigned int unsigned word 4
[signed] long signed word 4
unsigned long unsigned word 4
[signed] long long signed double-word 8
unsigned long long unsigned double-word 8
float single precision (IEEE 754) 4
double double precision (IEEE 754) 8
Long double double precision (IEEE 754) 8
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Storage Specifiers
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auto (default)
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Local variable with local life time
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extern or global variable
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Variable defined outside function will have global scope
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static
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Preserve this variable even after its scope ends
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register,
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This variable has to be stored in CPU register. Variables used often can
be defined in this category from performance perspective. But keep in
mind the limited cpu registers
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Exercise : Data Types and Storage
Classifiers
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Define variables based on different storage classifiers and data type
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Check size of data type defined
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Check default initial value and memory location of different storage
classifiers
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#include <stdio.h> //Pre-processor
//This is First C Program
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int main() {
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printf("Hello, World! n"); //printf() function
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return 0;
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}
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