Page 132 - Programming Microcontrollers in C

Miscellaneous Functions 117

STRING OPERATIONS—Defined in string.h

strcat(s,t) concatenate t to s
strncat(s,t,n) concatenate n characters of t to s
strcmp(s,t) return negative, 0, or positive
for s< t, s==t, or s>t respectively
strncmp(s,t,n) compare n characters of t and s
strcpy(s,t) copy t to s
strncpy(s,t,n) copy n characters of t to s
strchr(s,c) point to the first c in s or ‘\0’
strrchr(s,c) point to last c in s or ‘\0’

CHARACTER TESTS—in ctype.h

isalpha(c) non-zero if c is alphabetic, 0 if not
isupper(c) non-zero if c is uppercase, 0 if not
islower(c) non-zero if c is lowercase, 0 if not
isdigit(c) non-zero if c is a digit, 0 if not
isxdigit(c) non-zero if c is a hexadecimal digit, 0 if not
isalnum(c) non-zero if c is a digit or alphabetic, zero if not
isspace(c) non-zero if c is a blank, tab, newline,
return, formfeed, vertical tab, 0 if not
ispunct(c) non-zero if c is a printing character except
space, letter, or digit
iscntrl(c) non-zero if c is a control character, 0 if not
isgraph(c) non-zero if printing character except space
isprint(c) non-zero if printing character including space
toupper(c) return c converted to upper case
tolower(c) return c converted to lower case

MATH FUNCTIONS—in math.h
sin(x) sine of x, x in radians
cos(x) cosine of x, x in radians
tan(x) tangent of x, x in radians
asin(x) arcsine of x, -1<=x<=1
acos(x) arccosine of x, -1<=x<=1
atan2(x,y) four quadrant arctan of y/x, in radians
atan(x) two quadrant arctan of x, in radians
sinh(x) hyperbolic sine of x