Chapter 1

Introduction

Print Hello World

#include <stdio.h> // include information about standard library
main(){ //function name
	printf("hello, world");
}

• file ends in ".c", compile it with command cc hello.c

Variables and Arithmetic Expression

#include <stdio.h>
main(){
	int fahr, celsius;
	int lower, upper, step;
}

The For Statement

#include <stdio.h>
main(){
	int fahr;
for (fahr = 0; farh <= 300; fahr = fahr + 20)
		printf("%3d %5.1f\\n, fahr, (5.0/9.0)*(fahr-30));
}

• #define line defines a symbolic name or constant
• %3d right justifies using 3 digits
• %5.1f This means right justified using 5 columns, with 1 of those 5 after the decimal point

#define LOWER 0
#define UPPER 300

• name in upper case, do not need ;

c = getchar(); //reads the next input character
putchar(c);  //print the character

• The simplest (i.e., most primitive) form of character I/O is getchar() and putchar(), which read and print a single character

• EOF(end of file) is an integer defined in <stdio.h>

• scanf() is one of the commonly used function to take input from the user

  • reads formatted input from the standard input such as keyboards

  #include <stdio.h>
  int main()
  {
      int testInteger;
      printf("Enter an integer: ");
      scanf("%d", &testInteger);  
      printf("Number = %d",testInteger);
      return 0;
  }
  

  • &testInteger gets the address of testInteger

ASCII Value

#include <stdio.h>
int main()
{
    char chr;
    printf("Enter a character: ");
    scanf("%c", &chr);     

    // When %c is used, a character is displayed
    printf("You entered %c.\\n",chr);  

    // When %d is used, ASCII value is displayed
    printf("ASCII value is %d.", chr);  
    return 0;
}