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Basic-Syntax-variable-data-types-for-c

what is programming?

-Programming is the process of creating specific instructions—or code—that tell a computer how to perform tasks, solve problems, or automate processes.

how c language work?

-C is a compiled, procedural programming language that works by translating human-readable source code into machine code that a computer's processor can execute directly

why c?

  • Its too structured and mother of programming language
  • There is no built in library or function so we can learn from 0.

1-1 Structure Of C Programming

  • it has two parts
    1. Head Part - hold the header files (saves time and make us avoid some complicated code running behind the scene)
    2. Main Part - Holds the main code

1-2 First C Program

  • c programming syntax
# include <stdio.h>
int main ()

{
    printf("hello world"); // we have not wrote the function of printing its coming from header file 
    return 0;
}
  • the stdio means the standard input and output

Running Our First C Code

# include <stdio.h>
int main () // this is the main function and its a function return type

{
    printf("hello world"); // we have not wrote the function of printing its coming from header file 
    return 0; // return 0 means the code has run successfully
}
  • c programming starts to execute from main function

Printing in C

#include<stdio.h>
int main()
{
    printf("I am Sazid\n"); // for printing with brake \n is used 
    printf("demon\n");
    printf("dem\ton");
    return 0;
}
  • for printing with brake \n is used
  • for the Tab Space we can use \t

Variable and Data Type

  1. int -> -100, 0, 100
  2. float -> -2.5, 5.46
  3. char -> 'a', 'A', '@', 'H'
  4. boolean -> True or False

Variables in C

data-type variable name 

#include<stdio.h>
int main()
{
    int num; // declaring avariable will be stored in memory and we will assign data. 
    num=10;
    // or we can also write 
    int num1 = 10; 
    num1 = 20;
    float f = 3.56;
    char c = 'i am sazid';
    return 0;
}

  • variable is stored in memory and value is assigned and the code will be executed line by line

  • int holds 4 byte space in memory, float holds 4 byte space in memory, char holds 1 byte space in memory

  • 1 byte means 8 bit. 010101(here is 6 bit) as compute understand 0 and 1 these are bit.

  • 1024 bit means 1 kb

  • 1024 kb means 1 mb

  • 1024 mb means 1 gb

  • 1024 gb means 1 tb

print a variable

#include<stdio.h>
int main()
{
    int num; // declaring avariable will be stored in memory and we will assign data. 
    num=10;
    // or we can also write 
    int num1 = 10; 
    num1 = 20;
    float f = 3.56;
    char c = 'i am sazid';
    printf("num1"); // we cant print like this 
    return 0;
}
  • we cant print like this We need format specifier for printing variables
  1. int -> %d
  2. float -> %f
  3. char -> %c
#include<stdio.h>
int main()
#include<stdio.h>
int main()
{
    int num; // declaring avariable will be stored in memory and we will assign data. 
    num=10;
    // or we can also write 
    int num1 = 10; 
    num1 = 20;
    float f = 3.56;
    char c = 'i am sazid';
    // printf("num1"); // we cant print like this 
    printf("%d", num1);
    printf("%f", f);
    printf("%2f", f);
    printf("%c", c);
    return 0;
}

Boolean in c

  • boolean datatype is hold in another header
#include<stdbool.h>
  • print
#include<stdio.h>
#include<stdbool.h>
int main()
{
bool b;
b = false;
printf("%d", b); // boolean has no format specifier so we will be using the integer specifier as it only about 0 and 1 
return 0;
}

how to take input

  • for taking input we need a function name scanf() same as printf. we also need a format specifier for this
#include <stdio.h>
int main()
{
    int a;
    scanf("%d", &a); // it will take file and keep in a . its like as int is defined and defined a garbage value (0 or other) and the scanf will replace the taken input value. & meas the address of a . its responsible for changing the value
    printf("%d", a);
    return 0;
}

#include <stdio.h>
int main()
{
    int a;
    float f;
    char c;
    scanf("%d", &a); // it will take file and keep in a . its like as int is defined and defined a garbage value (0 or other) and the scanf will replace the taken input value. & meas the address of a . its responsible for changing the value
    scanf("%f", &f);
    scanf(" %c", &c); 

    printf("%d\n", a);
    printf("%c\n", c);
    printf("%f\n", f);

    // we can also take multiple fields as well
    scanf("%d %f %c", &a, &f, &c);
    printf("%d\n%f\n%c\n", a, f, c);
    return 0;
}

data type limitations

  • data types has a fixed size. like large integer we have to use long long int -> size 8 byte
  • for large float we have to use double -> 8 byte

lets calculate the size of the data types or data

  • 1 bit mean either 0 or 1
  • 2 bit means -> 00, 01, 10, 11 we can keep 4 numbers
  • 3 bit means -> 000, 001, 010, 011, 100, 101, 110, 111

Lets make a pattern

  • 2 power is the base 1 bit means 2 power 1
  • 32 bits means 2 power 32 .
  • we can keep 10 to the power 9 value max to a integer if more we have to use long long int it can take 10 to the power 18
#include <stdio.h>
int main()
{
    long long int a;
    printf("%lld", a); // specifier will be lld 
    return 0;
}
  • for float we also have limitation
  • we have to use double
#include <stdio.h>
int main()
{
    double f;
    printf("%lf", f);
    return 0;
}

naming of variable

  1. ibrahim
  2. _ibrahim
  3. @rahim -> we cant do it
  4. 123rahim -> we cant do it
  5. alu 123 -> we cant do it
  6. epok_123
  7. rahim123
  8. rahim,karim -> we cant use it
  9. int -> we can do it (or any c reserved words)
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