Useful C Library Function

7/23/2019 Useful C Library Function

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C library function - pow()

DescriptionThe C library function double pow(double x, double y)returns xraised to the power of yi.e. xy.

DeclarationFollowing is the declaration for pow() function.

doublepow(doublex,doubley)

Parameters x This is the floating point base alue.

y This is the floating point power alue.

!eturn "alueThis function returns the result of raising xto the power y.

#xample

The following example shows the usage of pow() function.

#include

#include

intmain ()

{

printf("Value .! $ %lf&n",pow(.!,))'

printf("Value .! .* $ %lf",pow(.!,.*))'

return(!)'

+

$et us compile and run the aboe program that will produce the following result


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Value .! $ .!!!!!!

Value .! .* $ *.!*-

C library function - sqrt()

Description

The C library function double sqrt(double x)returns the s%uare root of x.

DeclarationFollowing is the declaration for s%rt() function.

doubles/rt(doublex)

Parameters

x This is the floating point alue.

!eturn "alue

This function returns the s%uare root of x.

#xample

The following example shows the usage of s%rt() function.

#include

#include

intmain ()

{


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printf("0/uare root of %lf is %lf&n",.!,s/rt(.!))'

printf("0/uare root of %lf is %lf&n",.!,s/rt(.!))'

return(!)'

+


0/uare root of .!!!!!! is .!!!!!!

0/uare root of .!!!!!! is .1!1

C library function - acos()

Description

The C library function double acos(double x)returns the arc cosine of xin radians.

Declaration

Following is the declaration for acos() function.

doubleacos(doublex)

Parameters

x This is the floating point alue in the interal &'*+.

!eturn "alue

This function returns principal arc cosine of x in the interal &, pi+ radians.


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#xample

The following example shows the usage of acos() function.

#include

#include

#de2ne34 .*1

intmain ()

{

doublex,ret,5al'

x $!.*'

5al $!.!634'

ret $acos(x)75al'

printf("8he arc cosine of %lf is %lf de9rees",x,ret)'

return(!)'

+


8he arc cosine of !.*!!!!! is .!! de9rees

C library function - cos()

Description

The C library function double cos(double x)returns the cosine of a radian angle x.


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Declaration

Following is the declaration for cos() function.

doublecos(doublex)

Parameters

x This is the floating point alue representing an angle expressed in radians.

!eturn "alue

This function returns the cosine of x.

#xample

The following example shows the usage of cos() function.

#include

#include

#de2ne34 .*1

intmain ()

{

doublex,ret,5al'

x $1!.!'

5al $34 6!.!'

ret $cos(x75al )'

printf("8he cosine of %lf is %lf de9rees&n",x,ret)'

x $*!.!'

5al $34 6!.!'

ret $cos(x75al )'


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printf("8he cosine of %lf is %lf de9rees&n",x,ret)'

return(!)'

+


8he cosine of 1!.!!!!!! is !.!!!!! de9rees

8he cosine of *!.!!!!!! is !.!!!!!! de9rees

C library function - exp()

Description

The C library function double exp(double x)returns the alue of eraised to the xthpower.

Declaration

Following is the declaration for exp() function.

doubleexp(doublex)

Parameters


!eturn "alueThis function returns the exponential alue of x.

#xample

The following example shows the usage of exp() function.


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#include

#include

intmain ()

{

doublex $!'

printf("8he exponential 5alue of %lf is %lf&n",x,exp(x))'

printf("8he exponential 5alue of %lf is %lf&n",x:,exp(x:))'

printf("8he exponential 5alue of %lf is %lf&n",x:,exp(x:))'

return(!)'

+


8he exponential 5alue of !.!!!!!! is .!!!!!!

8he exponential 5alue of .!!!!!! is .-

8he exponential 5alue of .!!!!!! is -.*!1

C library function - ceil()-dertisements

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Description

The C library function double ceil(double x) returns the smallest integer alue greater than or

e%ual to x.

Declaration
http://www.tutorialspoint.com/c_standard_library/math_h.htmhttp://www.tutorialspoint.com/c_standard_library/math_h.htmhttp://www.tutorialspoint.com/c_standard_library/math_h.htmhttp://www.tutorialspoint.com/c_standard_library/math_h.htm


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Following is the declaration for ceil() function.

doubleceil(doublex)

Parameters


!eturn "alue

This function returns the smallest integral alue not less than x.

#xample

The following example shows the usage of ceil() function.

#include

#include

intmain ()

{

;oat5al,5al,5al,5al'

5al $.1'

5al $.'

5al $.'

5al $.'

printf ("5alue $ %.lf&n",ceil(5al))'




return(!)'


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+


5alue $ .!

5alue $ .!

5alue $ .!

5alue $ .!

C library function - floor()

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Description

The C library function double floor(double x)returns the largest integer alue less than or e%ualto x.

Declaration

Following is the declaration for floor() function.

double;oor(doublex)

Parameters x This is the floating point alue.

!eturn "alue


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This function returns the largest integral alue not greater than x.

#xample

The following example shows the usage of floor() function.

#include

#include

intmain ()

{

;oat5al,5al,5al,5al'

5al $.1'

5al $.'

5al $.'

5al $.'

printf("Value $ %.lf&n",;oor(5al))'




return(!)'

+


Value $ .!Value $ .!

Value $ .!

Value $ .!


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C library function - fmod()

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Description

The C library function double fmod(double x, double y)returns the remainder of xdiided by y.

Declaration

Following is the declaration for fmod() function.

doublefmod(doublex,doubley)

Parameters

x This is the floating point alue with the diision numerator i.e. x.

y This is the floating point alue with the diision denominator i.e. y.

!eturn "alue

This function returns the remainder of diiding x/y.

#xample

The following example shows the usage of fmod() function.

#include

#include


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intmain ()

{

;oata,b'

intc'

a $*.'

b $.-'

c $'

printf("emainder of %f 6 %d is %lf&n",a,c,fmod(a,c))'

printf("emainder of %f 6 %f is %lf&n",a,b,fmod(a,b))'

return(!)'

+


emainder of *.!!!!! 6 is .!!!!!

emainder of *.!!!!! 6 .-!!!!! is .!!!!!

C library function - strcat()

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Description

The C library function char *strcat(char *dest, const char *src)appends the string pointed to

by srcto the end of the string pointed to by dest.

Declaration
http://www.tutorialspoint.com/c_standard_library/string_h.htmhttp://www.tutorialspoint.com/c_standard_library/string_h.htmhttp://www.tutorialspoint.com/c_standard_library/string_h.htmhttp://www.tutorialspoint.com/c_standard_library/string_h.htm


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Following is the declaration for strcat() function.

char7strcat(char7dest,constchar7src)

Parameters

dest'' This is pointer to the destination array which should contain a C string and should

be large enough to contain the concatenated resulting string.

src'' This is the string to be appended. This should not oerlap the destination.

!eturn "alue

This function returns a pointer to the resulting string dest.

#xample

The following example shows the usage of strcat() function.

#include

#include

intmain ()

{

charsrc=!,dest=!'

strcpy(src, "8his is source")'

strcpy(dest,"8his is destination")'

strcat(dest,src)'

printf("?inal destination strin9 @ A%sA",dest)'

return(!)'

+


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$et us compile and run the aboe program that will produce the following result0

?inal destination strin9 @ A8his is destination8his is sourceA

C library function - strncat()

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Description

The C library function char *strncat(char *dest, const char *src, size_t n)appends the string

pointed to by srcto the end of the string pointed to by destup to ncharacters long.

Declaration

Following is the declaration for strncat() function.

char7strncat(char7dest,constchar7src,siBeCtn)

Parameters

dest'' This is pointer to the destination array which should contain a C string and should

be large enough to contain the concatenated resulting string which includes the additional

null'character.

src'' This is the string to be appended.

n'' This is the maximum number of characters to be appended.

!eturn "alue


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This function returns a pointer to the resulting string dest.

#xample

The following example shows the usage of strncat() function.

#include

#include

intmain ()

{

charsrc=!,dest=!'

strcpy(src, "8his is source")'

strcpy(dest,"8his is destination")'

strncat(dest,src,)'

printf("?inal destination strin9 @ A%sA",dest)'

return(!)'

+


?inal destination strin9 @ A8his is destination8his is sourceA

C library function - strchr()-dertisements

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Description

The C library function char *strchr(const char *str, int c)searches for the first occurrence of thecharacter c(an unsigned char) in the string pointed to by the argument str.

Declaration

Following is the declaration for strchr() function.

char7strchr(constchar7str,intc)

Parameters str'' This is the C string to be scanned.

c'' This is the character to be searched in str.

!eturn "alue

This returns a pointer to the first occurrence of the character c in the string str or 1$$ if the

character is not found.

#xample

The following example shows the usage of strchr() function.

#include

#include

intmain ()

{

constcharstr=$"[email protected]" '

constcharch $D.D'

char7ret'


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ret $strchr(str,ch)'

printf("0trin9 after A%cA is E A%sA&n",ch,ret)'

return(!)'

+


0trin9 after A.A is E A.tutorialspoint.comA

C library function - strcmp()

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Description

The C library function int strcmp(const char *str1, const char *str)compares the string pointed

to by str1to the string pointed to by str.

Declaration

Following is the declaration for strcmp() function.

intstrcmp(constchar7str,constchar7str)

Parameters

str1'' This is the first string to be compared.


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str'' This is the second string to be compared.

!eturn "alue

This function return alues that are as follows0

if !eturn alue 2 , then it indicates str is less than str3.

if !eturn alue 4 , then it indicates str3 is less than str.

if !eturn alue 5 , then it indicates str is e%ual to str3.

#xample

The following example shows the usage of strncmp() function.

#include

#include

intmain ()

{

charstr='

charstr='

intret'

strcpy(str,"abcdef")'

strcpy(str,"FGHIJ?")'

ret $strcmp(str,str)'

if(ret


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elseif(ret >!)

{

printf("str is less than str")'

+

else

{

printf("str is e/ual to str")'

+

return(!)'

+


str is less than str

C library function - strncmp()

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Description

The C library function int strncmp(const char *str1, const char *str, size_t n) compares at most

the first nbytes of str1and str.

Declaration

Following is the declaration for strncmp() function.


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intstrncmp(constchar7str,constchar7str,siBeCtn)

Parameters

str1'' This is the first string to be compared.

str'' This is the second string to be compared.

n'' The maximum number of characters to be compared.

!eturn "alue

This function return alues that are as follows0

if !eturn alue 2 , then it indicates str is less than str3.

if !eturn alue 4 , then it indicates str3 is less than str.

if !eturn alue 5 , then it indicates str is e%ual to str3.

#xample

The following example shows the usage of strncmp() function.

#include

#include

intmain ()

{

charstr='

charstr='

intret'

strcpy(str,"abcdef")'

strcpy(str,"FGHIJ?")'


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ret $strncmp(str,str,)'

if(ret


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The C library function char *strcpy(char *dest, const char *src)copies the string pointed to

by srcto dest.

Declaration

Following is the declaration for strcpy() function.

char7strcpy(char7dest,constchar7src)

Parameters

dest'' This is the pointer to the destination array where the content is to be copied.

src'' This is the string to be copied.

!eturn "alue

This returns a pointer to the destination string dest.

#xample

The following example shows the usage of strcpy() function.

#include

#include

intmain()

{

charsrc=!'

chardest=!!'

memset(dest,D&!D,siBeof(dest))'

strcpy(src,"8his is tutorialspoint.com")'

strcpy(dest,src)'


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printf("?inal copied strin9 @ %s&n",dest)'

return(!)'

+


?inal copied strin9 @ 8his is tutorialspoint.com

C library function - strncpy()

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Description

The C library function char *strncpy(char *dest, const char *src, size_t n)copies up

to ncharacters from the string pointed to by srcto dest. 6n a case where the length of src is less

than that of n the remainder of dest will be padded with null bytes.

Declaration

Following is the declaration for strncpy() function.

char7strncpy(char7dest,constchar7src,siBeCtn)

Parameters

dest'' This is the pointer to the destination array where the content is to be copied.

src'' This is the string to be copied.


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n'' The number of characters to be copied from source.

!eturn "alue

This function returns the final copy of the copied string.

#xample

The following example shows the usage of strncpy() function. 7ere we hae used function

memset() to clear the memory location.

#include

#include

intmain()

{

charsrc=!'

chardest='

memset(dest,D&!D,siBeof(dest))'

strcpy(src,"8his is tutorialspoint.com")'

strncpy(dest,src,!)'

printf("?inal copied strin9 @ %s&n",dest)'

return(!)'

+


?inal copied strin9 @ 8his is tu


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library function - strlen()

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Description

The C library function size_t strlen(const char *str)computes the length of the string strup to but

not including the terminating null character.

Declaration

Following is the declaration for strlen() function.

siBeCtstrlen(constchar7str)

Parameters

str'' This is the string whose length is to be found.

!eturn "alue

This function returns the length of string.

#xample

The following example shows the usage of strlen() function.

#include

#include


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intmain ()

{

charstr=!'

intlen'

strcpy(str,"8his is tutorialspoint.com")'

len $strlen(str)'

printf("Ken9th of A%sA is A%dA&n",str,len)'

return(!)'

+


Ken9th of A8his is tutorialspoint.comA is A1A

C library function - strstr()

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DescriptionThe C library function char *strstr(const char *haystac!, const char *needle) function finds the

first occurrence of the substring needlein the string haystac!. The terminating 89,8 characters are

not compared.

Declaration


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Following is the declaration for strstr() function.

char7strstr(constchar7haystacL,constchar7needle)

Parameters

haystac!'' This is the main C string to be scanned.

needle'' This is the small string to be searched with'in haystac: string.

!eturn "alue

This function returns a pointer to the first occurrence in haystac: of any of the entire se%uence of

characters specified in needle or a null pointer if the se%uence is not present in haystac:.

#xample

The following example shows the usage of strstr() function.

#include

#include

intmain()

{

constcharhaystacL=!$"8utorials3oint"'

constcharneedle=!$"3oint"'

char7ret'

ret $strstr(haystacL,needle)'

printf("8he substrin9 is@ %s&n",ret)'

return(!)'

+


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8he substrin9 is@ 3oint

C library function - strpbr!()

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Description

The C library function char *strpbr!(const char *str1, const char *str) finds the first character in

the string str1that matches any character specified in str. This does not include the terminating

null'characters.

Declaration

Following is the declaration for strpbr:() function.

char7strpbrL(constchar7str,constchar7str)

Parameters

str1'' This is the C string to be scanned.

str'' This is the C string containing the characters to match.

!eturn "alue

This function returns a pointer to the character in str that matches one of the characters in str3 or

1$$ if no such character is found.


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#xample

The following example shows the usage of strpbr:() function.

#include

#include

intmain ()

{

constcharstr=$"abcdef9hiMLl"'

constcharstr=$""'

char7ret'

ret $strpbrL(str,str)'

if(ret)

{

printf("?irst matchin9 character@ %c&n",7ret)'

+

else

{

printf("Hharacter not found")'

+

return(!)'

+


?irst matchin9 character@


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C library function - strto!()

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Description

The C library function char *strto!(char *str, const char *delim)brea:s string strinto a series of

to:ens using the delimiter delim.

Declaration

Following is the declaration for strto:() function.

char7strtoL(char7str,constchar7delim)

Parameters

str'' The contents of this string are modified and bro:en into smaller strings (to:ens).

delim'' This is the C string containing the delimiters. These may ary from one call to

another.

!eturn "alue

This function returns a pointer to the last to:en found in the string. - null pointer is returned if there

are no to:ens left to retriee.

#xample

The following example shows the usage of strto:() function.


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#include

#include

intmain()

{

charstr=!$"8his is E www.tutorialspoint.com E website"'

constchars=$"E"'

char7toLen'

67 9et the 2rst toLen 76

toLen $strtoL(str,s)'

67 walL throu9h other toLens 76

while(toLen N$OPKK )

{

printf(" %s&n",toLen )'

toLen $strtoL(OPKK,s)'

+

return(!)'

+


8his is

www.tutorialspoint.com

website

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Useful C Library Function