Name | Desc |
abort() | It terminates the C program |
abs() | This function returns the absolute value of an integer . The absolute value of a number is always positive. Only integer values are supported in C. |
asctime | Convert Date and Time to ASCII |
asctime() | Tm structure contents are interpreted by this function as calendar time. This time is converted into string. |
assert() | This function gets an integer as paramenter. If this paramenter is 0, writes message to stderr. Then, terminates the program. If this paramenter is non 0, it does nothing. |
atexit | Register Function to be Called at Program Exit |
atof() | Converts string to float |
atoi() | Converts string to int |
atol() | Converts string to long |
bsearch | Binary Search |
calloc() | This function is also like malloc () function. But calloc () initializes the allocated memory to zero. But, malloc() doesn’t |
ceil() | This function returns nearest integer value which is greater than or equal to the argument passed to this function. |
clearerr() | This function clears the error indicators |
clock() | This function is used to get current system time |
clrscr() | This function is used to clear the output screen. |
cos() | This function is used to calculate cosine. |
cosh() | This function is used to calculate hyperbolic cosine. |
ctime() | This function is used to return string that contains date and time informations |
delay() | This function Suspends the execution of the program for particular time |
difftime() | This function is used to get the difference between two given times |
div() | This function performs division operation |
errno() | This function sets errno value to 0 at the beginning of the program. This value is modified to other than 0 when an error occurs while any function call. |
exit() | This function terminates the program and does not return any value |
exp() | This function is used to calculate the exponential “e” to the xth power. |
fclose() | closes an opened file |
feof() | finds end of file |
ferror | Test for File Error |
fflush() | flushes a file |
fgetc() | reads a character from file |
fgetchar | reads a character from keyboard |
fgetpos | Get File Position |
fgets() | reads string from a file, one line at a time |
floor() | This function returns the nearest integer which is less than or equal to the argument passed to this function. |
fopen() | All file handling functions are defined in stdio.h header file |
fprintf() | writes formatted data to a file |
fputc() | writes a character to file |
fputchar | writes a character from keyboard |
fputs() | writes string to a file |
fread | Read Block from File |
free() | This function frees the allocated memory by malloc (), calloc (), realloc () functions and returns the memory to the system. |
freopen | Reopen File |
fscanf() | reads formatted data from a file |
fseek() | moves file pointer position to given location |
fsetpos | Set File Position |
ftell() | gives current position of file pointer |
fwrite | Write Block to File |
getc() | It reads character from file |
getdate() | This function is used to get the CPU time |
getenv() | This function gets the current value of the environment variable |
getch() | It reads character from keyboard |
getchar() | It reads character from keyboard |
getche() | It reads character from keyboard and echoes to o/p screen |
gets() | It reads line from keyboard |
getw() | reads an integer from file |
gmtime() | This function shares the tm structure that contains date and time informations |
isalnum() | checks whether character is alphanumeric |
isalpha() | checks whether character is alphabetic |
iscntrl() | checks whether character is a control character |
isdigit() | checks whether character is digit |
isgraph() | checks whether character is a graphical character |
islower() | checks whether character is lower case |
isprint() | checks whether character is a printable character |
ispunct() | checks whether character is a punctuation |
isspace() | checks whether character is space |
isupper() | checks whether character is upper case |
isxdigit() | checks whether character is hexadecimal |
labs | Absolute Value of Long Integer |
ldiv | Long Integer Division |
localeconv() | It gets locale conventions |
localtime() | This function shares the tm structure that contains date and time informations |
log() | This function is used to calculates natural logarithm. |
log10() | This function is used to calculates base 10 logarithm. |
longjmp() | It is used for non local jump |
malloc() | This function is used to allocate space in memory during the execution of the program. |
mblen | Compute Length of Multibyte Character |
mbstowcs | Convert Multibyte String to Wide Character String |
mbtowc | Convert Multibyte Character to Wide Character |
memcmp() | It is used to compare specified number of characters from two buffers |
memcpy() | It is used to copy a specified number of bytes from one memory to another |
memchr() | It is used to locate the first occurrence of the character in the specified string |
memicmp() | It is used to compare specified number of characters from two buffers regardless of the case of the characters |
memmove | Copy Memory Block |
memmove() | It is used to copy a specified number of bytes from one memory to another or to overlap on same memory. |
memset() | It is used to initialize a specified number of bytes to null or any other value in the buffer |
mktime() | This function interprets tm structure as calendar time |
perror() | This function displays most recent error that happened during library function call. |
pow() | This is used to find the power of the given number. |
printf() | This function is used to print the character, string, float, integer, octal and hexadecimal values onto the output screen |
putc() | writes a character to file |
putenv() | This function modifies the value for environment variable |
putchar() | It writes a character to screen |
puts() | It writes line to o/p screen |
putw() | writes an integer to file |
qsort | Sort Array |
raise() | It is used to raise signal in a C program |
rand() | This function returns the random integer numbers |
realloc() | This function modifies the allocated memory size by malloc () and calloc () functions to new size |
remove() | s a file |
rename | Rename File |
rewind() | moves file pointer position to the beginning of the file |
round() | This function returns the nearest integer value of the float/double/long double argument passed to this function. If decimal value is from ”.1 to .5″, it returns integer value less than the argument. If decimal value is from “.6 to .9″, it returns the integer value greater than the argument. |
scanf() | This function is used to read a character, string, numeric data from keyboard. |
setbuf | Set Buffer (obsolete) |
setdate() | This function used to modify the system date |
setenv() | This function sets the value for environment variable |
setjmp() | This function prepares to use longjmp() function |
setlocale() | It sets locale() |
setvbuf | Set Buffer |
signal() | It is used to install signal handler |
sin() | This function is used to calculate sine value. |
sinh() | This function is used to calculate hyperbolic sine. |
sprint() | writes formatted output to string |
sqrt() | This function is used to find square root of the argument passed to this function. |
srand | Seed Pseudo-Random Number Generator |
sscanf() | Reads formatted input from a string |
strcat(str1, str2) | Concatenates str2 at the end of str1. |
strcmp(str1, str2) | Returns 0 if str1 is same as str2. Returns <0 if strl < str2. Returns >0 if str1 > str2. |
strcmpi(str1,str2) | Same as strcmp() function. But, this function negotiates case. “A” and “a” are treated as same. |
strcoll | String Compare Using Locale-Specific Collating Sequence |
strcpy(str1, str2) | Copies str2 into str1 |
strcspn | Search String for Intial Span of Characters Not in Set |
strdup() | duplicates the string |
strerror | Convert Error Number to String |
strftime() | This function is used to modify the actual time format |
strchr(str1,char) | Returns pointer to first occurrence of char in str1. |
strlen(strl) | gives the length of str1. |
strlwr() | converts string to lowercase |
strncat() | appends a portion of string to another |
strncmp | Bounded String Compare |
strncpy() | copies given number of characters of one string to another |
strpbrk | Search String for One of a Set of Characters |
strrev() | reverses the given string |
strrchr() | last occurrence of given character in a string is found |
strset() | sets all character in a string to given character |
strspn | Search String for Initial Span of Characters in Set |
strstr(str1, str2) | Returns pointer to first occurrence of str2 in str1. |
strtod() | Converts string to double |
strtok() | tokenizing given string using delimiter |
strtol() | Converts string to long |
strtoll | Convert String to Long Long |
strtoul | Convert String to Unsigned Long Integer |
strupr() | converts string to uppercase |
strxfrm | Transform Locale-Specific String |
system() | This function is used to execute commands outside the C program. |
tan() | This function is used to calculate tangent. |
tanh() | This function is used to calculate hyperbolic tangent. |
textbackground() | This function is used to change text background |
textcolor() | This function is used to change the text color |
time() | This function is used to get current system time as structure |
tmpfile | Create Temporary File |
tmpnam | Generate Temporary File Name |
tolower() | checks whether character is alphabetic & converts to lower case |
toupper() | checks whether character is alphabetic & converts to upper case |
trunc() | This function truncates the decimal value from floating point value and returns integer value. |
ungetc | Unread Character |
va_arg() | This function is used to fetch the arguments from variable length argument list |
va_end() | This function indicates the end process of variable length argument list in a program |
va_start() | This function indicates the start process of variable length argument list in a program |
vfprintf | Formatted File Write Using Variable Argument List |
vprintf | Formatted Write Using Variable Argument List |
vsprintf | Formatted String Write Using Variable Argument List |
wcstombs | Convert Wide Character String to Multibyte String |
wctomb | Convert Wide Character to Multibyte Character |