Review of basic C programming
=============================

Basic Structure
---------------
e.g.
main()
{
printf("Hello World\n");
}

Basic Data Type (and printf conversion specification)
-----------------------------------------------------
* long double (%Lf)
* double (%f)
* float (%f)
* unsigned long int (%lu)
* long int (%ld)
* unsigned int (%u)
* int (%d)
* short (%hd)
* char (%c)
* void

Program Control
---------------
* For loop
e.g.
for (i=0;i<100;i++)
{
printf("i=%d\n",i);
}

* While loop
e.g.
i=0;
while (i<100)
{
printf("i=%d\n",i);
i++;
}

* Do-While loop
e.g.
i=0;
do
{
i++;
printf("i=%d\n",i);
} while (i<100);

* If-Then-Else control
e.g.
if (i>10)
{
printf("i is larger than 10\n");
}
else
{
printf("i is smaller than or equal to 10\n");
}

* break and continue
e.g.
for (i=0;i<100;i++)
{
if (i==20)
{
break;
}
printf("i=%d\n",i);
}

e.g.
for (i=0;i<100;i++)
{
if (i==20)
{
continue;
}
printf("i=%d\n",i);
}

* Switch-Case control
e.g.
switch (grade)
{
case 'A':
printf("grade A\n");
break;
case 'B':
printf("grade B\n");
break;
default:
printf("No good\n");
break;
}

Operators
---------
* &&, ||
* ()
* ++, --
* +, -, *, /, %
* !
* (type)
* <, <=, >, >=
* ==, !=
* ?:
* =, += , -=, *=, /=, %=


Functions
---------
* math functions (#include <math.h>)
- sqrt(x)
- exp(x)
- log(x)
- log10(x)
- fabs(x)
- ceil(x)
- floor(x)
- pow(x,y)
- fmod(x,y)
- sin(x)
- cos(x)
- tan(x)

* function definitions and prototype
e.g.
int square(int y);
main()
{
.......
b = square(a);
.......
}
int square(int y)
{
return y*y;
}

* header files
- #include <...>
- #include "..."

* calling functions: call by value and call by reference
e.g.
void changeit(int x);
main()
{
int a;
.......
changeit(a);
.......
}
void changeit(int x)
{
x = 10;
}

e.g.
void changeit(int *x);
main()
{
int a;
.......
changeit(&a);
.......
}
void changeit(int *x)
{
*x = 10;
}

* local and global scope
void printa();
int a=5;
main()
{
int a;

a = 10;
printa();
printf("a=%d\n",a);
}
void printa()
{
printf("a=%d\n",a);
a = 20;
}

* Recursion (non-iterative)
e.g.
long factorial(long number);
main()
{
factorial(10);
}
long factorial(long number);
{
if (number <= 1)
return 1;
else
return (number * factorial(number - 1));
}


Arrays
------
* start from zero

* declaration
e.g.
int c[5] = {3, 10, 22, 64, 23};

* as a constant pointer
- d = *(c+3);
- d = c[3];
- e = c + 2;
- e = &c[2];

* two dimensional array:
e.g.
int c[10][5];



Pointers
--------
* address in memory

* declaration
e.g.
int *countPtr, count;

* operators
e.g.
countPtr = &count;
*countPtr = 10;


Characters and Strings
----------------------
* character array
e.g.
char color[] = "blue";

* null terminate ('\0' or NULL)

* conversion functions
- atof
- atoi
- atol

* string manipulation functions
- strcpy
- strncpy
- strcat
- strncat
- strcmp
- strncmp


Input and Output
----------------
* getchar

* gets

* putchar

* puts

* sprintf

* sscanf

* printf
- for integer: %d, %i, %o, %u, %x
- for floating-point: %e, %f, %g
- for character: %c, %s
- field width and precision
e.g.
printf("%9.3f",123.456789);




Exercise
========
6.15 Use a single-subscripted array to solve the following problem. Read 20
numbers, each of which is between 10 and 100, inclusive. As each number is read,
print it only if it is not a duplicate of a number already read. Provide for the
"worst case" in which all 20 numbers are different. Use the smallest possible
array to solve this problem.

8.36 Dates are commonly printed in several different formats in business
correspondence. Two of the more common formats are:
07/21/55 and July 21, 1955
Write a program that reads a date in the first format and prints that date in
the second format.