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C language

Aug 18, 20254 min read

2024-07-3119:08 Status: Tags:

Structure

Command line interface (CLI)→ Linux +vs. GUI (IDEs = Text editors → Use Visual Studio Code ) (Source code → Compiler → Machine code) A terminal window allows you to run commands on code you create ($)

Header files = a menu of functions for example # include <stdio.h> and  <#include cs50.h> = are extensions to C

Data Types

Integer values (=4 bytes) ⇒ range = -2^31 - 2^31 - 1 (apx. 4 billion total) (Qualifiers) Unsigned integer ⇒ an integer value that ignores negative values

  • bool = true/false
  • char = a singular letter/symbol
  • double = long decimal value
  • float = decimal values
  • int = whole numbers
  • long = long integer values
  • string = a string of characters
  • %_
  • Char = 1 bit (256 values) ⇒ ASCII
  • Floating point numbers (=4 bytes) ⇒ A real number containing a decimal value.
  • Double (=64 bytes) Acts like a float but has more information
  • Void (is just a type (not a data type)) ⇒ Doesn’t return any information = doesn’t take any arguments
  • Bool = True/false
  • String = A collection of characters
  • Structs + type defs

(cast ___ (insert type here)) = convert to a different type (float) y (when y is an integer ⇒ it can be converted to a )

Constant = you cannot change a variable’s properties,

Operators

  • = addition
  • = subtraction
  • / = divide
    • = multiply
  • % = remainder (modulus)
  • <,⇐, >,>= = inequalities
  • == = equal to
  • != = not equal to
  • || = or (boolean expression)
  • && = and  (boolean expression)
  • != not/bang = inverses true/false (boolean expression)
  • ++ = +1
  • — = -1 // = notes within code int counter = counter + 1; (can also be written as…) counter+=1;  (you can use i as counter var.)
  • → It remembers the datatype and by using the += operator, you can simplify the program

Source

printf("hello world") = // Side affect = visual output
Return values = // Output of the function or program
string answer  = // get_string("What's your name? ");
string/int = //specifies what variable is, answer = variable, get_string()= function, "x" = displayed text
(=) = //assignment operator
$\n$ = //writes a new line
printf("hello, %s\n", answer);
= // %s put a string placeholder
= // %i put a integer placeholder
 
// To start a program use
int main(void)
{
... put all main code in here
}

If Else Conditionals

if //(boolean-expression)
{... }
 
if //(boolean-expression)
{... }
 
else
{...}
 
if//(boolean-expression)
{... }
 
else if
{...}
 
else
{....}
 
//(lack of breaks will entail a fall of cases)
 
int x = GetInt ();
switch(x)
{
case 1:
printf("One!\\n")
break;
case 2:
printf("Two!\\n")
break;
case 3:
printf("Three!\\n")
break;
default:
printf("Sorry!\\n")
}
 
int  x =  (expr) ? 5: 6;
//a very fast way of expressing an if else statement

Loops

//Loops:
//Forever loop:
 
While (true)
{...}
 
Repeat until loop:
While (expression)
{...}
 
//Use when the number of times used is unknown (maybe not at all)
//Do-while loop:
 
Do
{...}
while (expression);
//Use when you want the expression to run at least once
 
For loop
for (int i = 0; i < 10; i++(expression))
//for (start; expr; increment)
//set i as 0, and repeat an expression 10 times
//use for loops when you want an expression to be run a specified amount of times
//Setting an array example
int n = get_int(”How many tests did you have?”)
int score [n]; 
for (int i = 0; i < n; i++1)
 
{
scores [i] - get_int(”Score:”); 
}

Arrows

(pointer_name)->(variable_name)

foo->bar is equivalent to (*foo).bar, i.e. it gets the member called barfrom the struct that foopoints to. The operator ‘.’ is used to access the child object of…

Source(s)

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