cheatsheet_on_c.txt

// Environment variables:
C_INCLUDE_PATH=/opt/gdbm-1.8.3/include
export C_INCLUDE_PATH

/ Link path:
LIBRARY_PATH=/opt/gdbm-1.8.3/lib
export LIBRARY_PATH

// hello world

#include <stdio.h>

int main() {
    printf("Hello, World!\n");
    return 0;
}

/ Now, we can compile:
gcc main.c // it will produce a file named a.out that can be executed by doing ./a.out
//
# Print a float
int main() {
    float slope = 0.2;
    printf("Slope: %f\n", slope);
    return 0;
}

# Print an int
int main() {
  int anumber = 1;
  printf("%d\n", anumber);
  return 0;
}
###################################
##### Structs:
// A variable declaration with structure declaration. 
struct Point 
{ 
   int x, y; 
} p1;  // The variable p1 is declared with 'Point' 
  
  
// A variable declaration like basic data types 
struct Point 
{ 
   int x, y; 
};  
  
int main() 
{ 
   struct Point p1;  // The variable p1 is declared like a normal variable 
}

## Structure members can be initialized using curly braces ‘{}’. For example, following is a valid initialization.
struct Point 
{ 
   int x, y; 
};  
  
int main() 
{ 
   // A valid initialization. member x gets value 0 and y 
   // gets value 1.  The order of declaration is followed. 
   struct Point p1 = {0, 1};  
}

# How to access structure elements?
# Structure members are accessed using dot (.) operator.
#include<stdio.h> 

struct Point 
{ 
int x, y; 
}; 

int main() 
{ 
struct Point p1 = {0, 1}; 

// Accessing members of point p1 
p1.x = 20; 
printf ("x = %d, y = %d", p1.x, p1.y); 

return 0; 
}

# What is designated Initialization?
# Designated Initialization allows structure members to be initialized in any order. This feature has been added in C99 standard.
#include<stdio.h> 
  
struct Point 
{ 
   int x, y, z; 
}; 
  
int main() 
{ 
   // Examples of initialization using designated initialization 
   struct Point p1 = {.y = 0, .z = 1, .x = 2}; 
   struct Point p2 = {.x = 20}; 
  
   printf ("x = %d, y = %d, z = %d\n", p1.x, p1.y, p1.z); 
   printf ("x = %d", p2.x); 
   return 0;
}

# What is an array of structures?
# Like other primitive data types, we can create an array of structures.

#include<stdio.h> 
  
struct Point 
{ 
   int x, y; 
}; 
  
int main() 
{ 
   // Create an array of structures 
   struct Point arr[10]; 
  
   // Access array members 
   arr[0].x = 10; 
   arr[0].y = 20; 
  
   printf("%d %d", arr[0].x, arr[0].y); 
   return 0; 
} 
#########
#goog tutorial on arrays:
https://www.programiz.com/c-programming/c-arrays