Adapted from
Differences Between C and C++
by Robert Niemann (Century College)
11/22/2015

Adapted by Mithat Konar

• You can't create classes or objects in C.
• You can't use any of C++'s predefined classes and objects.
  • cin
  • cout
  • string
  • class
  • etc.

• Input/output is generally more complicated in C.

• printf() write a formatted string to the display
• scanf() read a formatted string from the keyboard
• putchar() write a single character to the display
• getchar() read a single character from the keyboard
• puts() write strings to the display
• gets() read a string from the keyboard

• fopen(), fclose() open/close a text file.
• feof() detect end-of-file marker in a file.
• fscanf() read formatted string from a file.
• fprintf() write formatted string to a file.
• fgets() read a string from a file.
• fputs() write a string to a file.
• fgetc() read single character from a file.
• fputc() write a single character to a file.

• <stdio.h> input/output
• <stdlib.h> standard utility functions
• <string.h> string operations
• <ctype.h> character class tests
• <math.h> mathematical functions

• boolean type
• reference variables
• function overloading
• // single line comments (in older versions of C).

• You must define variables at the beginning of a function.

  int  main( )
  {
      int a,b,c;
      float x,y,z;
      ...

• You don’t need function prototypes.

  int main()
  {
      foo();
      return 0;
  }
   
  int foo()
  {
      printf( "Hello world" );
  }

• Best practice to use them anyway.

• const is available only in newer versions of C.
• #define precompiler directive typically used instead for named constants.

  #define PI 3.1415
  #define TAX_RATE 0.065

• #define can also be used to create macros.

  #define square(x) ((x) * (x))

• Allocating/deallocating dynamic memory is different.

int *x = malloc(sizeof(int));            /* allocate a single int */
int *x_array = malloc(sizeof(int) * 10); /* allocate array of 10 ints */
 
/* release storage that was allocated */
free( x );
free( x_array );

• Need to use struct keyword when defining struct variables.

  struct MyStruct
  {
      int x;
  };
   
  struct MyStruct aStructInstance;

• Look here.

• C Reference Card (ANSI)
• A C Tutorial from Tutorials Point