C Tutorials

Basics in C

Introduction of C
Keywords in C
Data Types in C
First Program in C
Add Two Numbers in C
Input from User in C
String Input from User in C

Decision Making

If Statement in C
If and Else Statement in C
AND Operator in If Statement in C
Switch Statement in C

Loops

While Loop in C
While Loop User Input in C
Triangle using While Loop in C
For Loop in C
For Loop using Continue in C
Do While Loop in C
Triangle using Do While Loop in C

Functions

Function in C
Calling Function inside Function in C
Passing Arguments to Function in C
Passing String Arguments to Function in C
Passing Arguments to Function and Return in C
Calling Function of .h File in C

Arrays

Array in C
String Array in C
User Input in Array in C
Find Min and Max Number in Array in C
Two Dimensional Array in C
User Input using Gets and Puts in C

Pointers

Pointers in C
Working with Pointers in C
String Functions in C

Structure

Structure in C
Passing Arguments in Structure in C
Passing Arguments and Return in Structure in C
Constructor in Structure in C

Data and Time

Date and Time in C

File Handling

Read and Write Text File in C
Deleting File in C
Create and Delete Directory in C
File Opening Modes in C

More Examples

Encryption and Decryption in C
Open Application in C
Defining Startup and Exit in C
Working with Define in C
View Address of Variable in C
Shut Down Computer in C

Library Functions

Precedence Table in C
Arithmetic Functions in C
IO Functions in C
Disk IO Functions in C
Basic Data Types Meanings in C
Printf Format Specifiers in C
Library Header Files in C

Disk I/O Functions in C

Disk I/O, memory allocation, time-related, and miscellaneous functions in C programming with descriptions are listed below. You can use the following functions to work with values.

Disk I/O Functions

Function	Use
absread	Reads absolute disk sectors.
abswrite	Writes absolute disk sectors.
biosdisk	Performs BIOS disk services.
getdisk	Gets current drive number.
setdisk	Sets current disk drive.

Memory Allocation Functions

Function	Use
calloc	Allocates a block of memory.
farmalloc	Allocates memory from far heap.
farfree	Frees a block from far heap.
free	Frees a block allocated with malloc.
malloc	Allocates a block of memory.
realloc	Reallocates a block of memory.

Process Control Functions

Function	Use
abort	Aborts a process.
atexit	Executes function at program termination.
execl	Executes child process with argument list.
exit	Terminates the process.
spawnl	Executes child process with argument list.
spawnlp	Executes child process using PATH variable and argument list.
system	Executes an MS-DOS command.

Graphics Functions

Function	Use
arc	Draws an arc.
ellipse	Draws an ellipse.
floodfill	Fills an area of the screen with the current color.
getimage	Stores a screen image in memory.
getlinestyle	Obtains the current line style.
getpixel	Obtains the pixel's value.
lineto	Draws a line from the current graphic output position to the specified point.
moveto	Moves the current graphic output position to a specified point.
pieslice	Draws a pie-slice-shaped figure.
putimage	Retrieves an image from memory and displays it.
rectangle	Draws a rectangle.
setcolor	Sets the current color.
setlinestyle	Sets the current line style.
putpixel	Plots a pixel at a specified point.
setviewport	Limits graphic output and positions the logical origin within the limited area.

Time Related Functions

Function	Use
clock	Returns the elapsed CPU time for a process.
difftime	Computes the difference between two times.
ftime	Gets current system time as structure.
strdate	Returns the current system date as a string.
strtime	Returns the current system time as a string.
time	Gets current system time as long integer.
setdate	Sets DOS date.
getdate	Gets system date.

Miscellaneous Functions

Function	Use
delay	Suspends execution for an interval (milliseconds).
getenv	Gets value of environment variable.
getpsp	Gets the Program Segment Prefix.
perror	Prints error message.
putenv	Adds or modifies value of environment variable.
random	Generates random numbers.
randomize	Initializes random number generation with a random value based on time.
sound	Turns PC speaker on at specified frequency.
nosound	Turns PC speaker off.

DOS Interface Functions

Function	Use
FP_OFF	Returns offset portion of a far pointer.
FP_SEG	Returns segment portion of a far pointer.
getvect	Gets the current value of the specified interrupt vector.
keep	Installs terminate-and-stay-resident (TSR) programs.
int86	Issues interrupts.
int86x	Issues interrupts with segment register values.
intdos	Issues interrupt 21h using registers other than DX and AL.
intdosx	Issues interrupt 21h using segment register values.
MK_FP	Makes a far pointer.
segread	Returns current values of segment registers.
setvect	Sets the current value of the specified interrupt vector.

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