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# Alphabetical Listing of C Functions

Click on a function for more information:

Function Name | Description
abs | Gets the absolute value of an integer.
asctime | Converts time from a structure to a string.
atof | Converts a string to a floating point value.
atoi | Converts a string to an integer value.
atol | Converts a string to a long integer value.
calloc | Allocates an array and initializes all elements to zero.
char | Defines a variable to store a character
chdir | Changes the current directory to the given path. (Windows only)
chdrive | Switches to another drive.
cos | Computes the cosine of an angle in radians.
ctime | Converts the calendar time to local time.
fclose | Closes a file.
feof | Checks if the end of file has occurred on a stream.
ferror | Checks if any error has occurred during file I/0.
fgetc | Gets a character from a stream.
fgets | Reads a string from a file.
ftell | Returns the current file position of the given stream.
floor | Gets the largest integral value that is less than x.
fopen | Opens a file for buffered I/0.
fprintf | Writes formatted output to a file.
fputc | Writes a character to a stream.
fread | Reads unformatted data from a stream into a buffer.
free | Frees a block of memory.
fscanf | Reads formatted input from a stream.
fseek | Sets the current position in a file to a new location.
fwrite | Write unformatted data from a buffer to a stream.
getcwd | Returns the name of the current working directory.
getdrive | Returns the name of the current drive.
getenv | Gets the definition of an environment variable.
gmtime | Converts the calendar time into Coordinated Universal Time (UTC).
isalpha | Checks if a string is a letter.
isdigit | Checks if a string is a decimal digit.
localtime | Converts the calendar time into local time.
malloc | Allocates a block of memory.
memchr | Searches for a character in a buffer.
memcmp | Compares two buffers.
memcpy | Copies n characters from one buffer into another.
memmove | Moves a number of bytes from one buffer to another.
memset | Sets n bytes of a buffer to a given character.
mkdir | Creates a directory using the given path name.
putenv | Inserts a new definition into an environment table.
rand | Gets a random integer between 0 and 32767.
realloc | Reallocates (adjusts the size of) a block of memory.
remove | Deletes the specified file.
rewind | Rewinds a file.
rmdir | Deletes the specified directory.
sin | Computes the sine of an angle in radians.
sprintf | Writes formatted output to a string.
sqrt | Computes the square root of x.
sscanf | Reads formatted input from a string.
strcat | Concatenates two strings.
strchr | Returns the pointer to the first occurrence of a character in a string.
strcmp | Compares two strings to determine the alphabetic order.
strcpy | Copies one string to another.
strdup | Duplicates a string.
strftime | Converts time to a string, and writes the string into a memory area.
stricmp | Performs a case-insensitive comparison of two strings.
strlen | Returns the length of a string.
strncat | Concatenates n characters from one string to another.
strncmp | Compares the first n characters of two strings.
strncpy | Copies the first n characters of one string to another.
strnicmp | Performs a case-insensitive comparison between n characters from two strings, to determine the alphabetic order.
strrchr | Finds the last occurrence of a character in a string.
strspn | Returns the length of the leading characters in a string that are contained in a specified string.
strstr | Returns the first occurrence of one string in another.
strtok | Returns a token from a string delimited by specified characters.
strtol | Converts a string to a long integer using a given radix.
system | Executes an operating system command.
time | Returns the current calendar time.
tolower | Converts a character to lowercase.
toupper | Converts a character to uppercase.

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