Functions are reusable code blocks. Which can do a certain job. There are many such functions written in C programming. These are called library functions.
stdio.h: I/O functions:
getchar() returns the next character typed on the keyboard.
putchar() outputs a single character to the screen.
printf() as previously described
scanf() as previously described
string.h: String functions
strcat() concatenates a copy of str2 to str1
strcmp() compares two strings
strcpy() copys contents of str2 to str1
ctype.h: Character functions
isdigit() returns non-0 if arg is digit 0 to 9
isalpha() returns non-0 if arg is a letter of the alphabet
isalnum() returns non-0 if arg is a letter or digit
islower() returns non-0 if arg is lowercase letter
isupper() returns non-0 if arg is uppercase letter
math.h: Mathematics functions
acos() returns arc cosine of arg
asin() returns arc sine of arg
atan() returns arc tangent of arg
cos() returns cosine of arg
exp() returns natural logarithim e
fabs() returns absolute value of num
sqrt() returns square root of num
time.h: Time and Date functions
time() returns current calender time of system
difftime() returns difference in secs between two times
clock() returns number of system clock cycles since program execution
stdlib.h:Miscellaneous functions
malloc() provides dynamic memory allocation, covered in future sections
rand() as already described previously
srand() used to set the starting point for rand()
Library functions
Reviewed by increaseidea
on
April 27, 2020
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