C++ Reference c:string

atof

2008-09-06T11:26:18-07:00

atof Syntax: #include double atof( const char *str ); The function atof() converts str into a double, then returns that value. str must start with a valid number, but can be terminated with any non-numerical character, other than “E” or “e”. For example,

atoi

2009-02-18T14:51:07-07:00

atoi Syntax: #include int atoi( const char *str ); The atoi function converts str into an integer, and returns that integer. str should start with whitespace or some sort of number, and atoi will stop reading from str as soon as a non-numerical character has been read. For example:

atol

2008-12-06T16:53:45-07:00

atol Syntax: #include long atol( const char *str ); The function atol() converts str into a long, then returns that value. atol() will read from str until it finds any character that should not be in a long. The resulting truncated value is then converted and returned. For example,

isalnum

2009-03-22T17:18:47-07:00

isalnum Syntax: #include int isalnum( int ch ); The function isalnum() returns non-zero if its argument is a numeric digit or a letter of the alphabet. Otherwise, zero is returned. char c; scanf( "%c", &c ); if( isalnum(c) ) printf( "You entered the alphanumeric character %c\n", c );

isalpha

2008-10-14T15:42:02-07:00

isalpha Syntax: #include int isalpha( int ch ); The function isalpha() returns non-zero if its argument is a letter of the alphabet. Otherwise, zero is returned. char c; scanf( "%c", &c ); if( isalpha(c) ) printf( "You entered a letter of the alphabet\n" );

iscntrl

2008-10-14T15:42:02-07:00

iscntrl Syntax: #include int iscntrl( int ch ); The iscntrl() function returns non-zero if its argument is a control character (between 0 and 0x1F or equal to 0x7F). Otherwise, zero is returned. Related Topics: isalnum, isalpha, isdigit, isgraph, isprint, ispunct, isspace, isxdigit

isdigit

2009-11-27T05:53:47-07:00

isdigit Syntax: #include int isdigit( int ch ); The function isdigit() returns non-zero if its argument is a digit between 0 and 9. Otherwise, zero is returned. char c; scanf( "%c", &c ); if( isdigit(c) ) printf( "You entered the digit %c\n", c );

isgraph

2008-10-14T15:42:02-07:00

isgraph Syntax: #include int isgraph( int ch ); The function isgraph() returns non-zero if its argument is any printable character other than a space (if you can see the character, then isgraph() will return a non-zero value). Otherwise, zero is returned.

islower

2008-10-14T15:42:02-07:00

islower Syntax: #include int islower( int ch ); The islower() function returns non-zero if its argument is a lowercase letter. Otherwise, zero is returned. Related Topics: isupper

isprint

2008-10-14T15:42:02-07:00

isprint Syntax: #include int isprint( int ch ); The function isprint() returns non-zero if its argument is a printable character (including a space). Otherwise, zero is returned. Related Topics: isalnum, isalpha, iscntrl, isdigit, isgraph, ispunct, isspace

ispunct

2008-10-14T15:42:02-07:00

ispunct Syntax: #include int ispunct( int ch ); The ispunct() function returns non-zero if its argument is a printing character but neither alphanumeric nor a space. Otherwise, zero is returned. Related Topics: isalnum, isalpha, iscntrl, isdigit, isgraph, isprint, isspace, isxdigit

isspace

2008-10-14T15:42:02-07:00

isspace Syntax: #include int isspace( int ch ); The isspace() function returns non-zero if its argument is some sort of space (i.e. single space, tab, vertical tab, form feed, carriage return, or newline). Otherwise, zero is returned.

isupper

2008-10-14T15:42:02-07:00

isupper Syntax: #include int isupper( int ch ); The isupper() function returns non-zero if its argument is an uppercase letter. Otherwise, zero is returned. Related Topics: islower, tolower

isxdigit

2009-06-09T08:46:20-07:00

isxdigit Syntax: #include int isxdigit( int ch ); The function isxdigit() returns non-zero if its argument is a hexadecimal digit (i.e. A-F, a-f, or 0-9). Otherwise, zero is returned. Related Topics: isalnum, isalpha, iscntrl, isdigit, isgraph, ispunct, isspace

memchr

2008-10-14T15:42:02-07:00

memchr Syntax: #include void *memchr( const void *buffer, int ch, size_t count ); The memchr() function looks for the first occurrence of ch within count characters in the array pointed to by buffer. The return value points to the location of the first occurrence of ch, or NULL if ch isn't found. For example:

memcmp

2008-09-17T17:28:40-07:00

memcmp Syntax: #include int memcmp( const void *buffer1, const void *buffer2, size_t count ); The function memcmp() compares the first count characters of buffer1 and buffer2. The return values are as follows: Value Explanationless than 0 buffer1 is less than buffer2equal to 0 buffer1 is equal to buffer2greater than 0 buffer1 is greater than buffer2 Related Topics: memchr, memcpy, memset, strcmp

memcpy

2008-10-14T15:42:02-07:00

memcpy Syntax: #include void *memcpy( void *to, const void *from, size_t count ); The function memcpy() copies count characters from the array from to the array to. The return value of memcpy() is to. The behavior of memcpy() is undefined if to and from overlap.

memmove

2008-10-14T15:42:02-07:00

memmove Syntax: #include void *memmove( void *to, const void *from, size_t count ); The memmove() function is identical to memcpy(), except that it works even if to and from overlap. Related Topics: memcpy, memset

memset

2009-09-15T08:03:38-07:00

memset Syntax: #include void* memset( void* buffer, int ch, size_t count ); The function memset copies ch into the first count characters of buffer, and returns buffer. memset is useful for intializing a section of memory to some value. For example, this command:

Standard C String and Character

2010-06-17T11:27:13-07:00

atofconverts a string to a doubleatoiconverts a string to an integeratolconverts a string to a longisalnumtrue iff a character is alphanumericisalphatrue iff a character is alphabeticiscntrltrue iff a character is a control characterisdigittrue iff a character is a digitisgraphtrue iff a character is a graphical characterislowertrue iff a character is lowercaseisprinttrue iff a character is a printing characterispuncttrue iff a character is punctuationisspacetrue iff a character is a space chara…

strcat

2009-04-06T11:13:00-07:00

strcat Syntax: #include char *strcat( char *str1, const char *str2 ); The strcat function concatenates str2 onto the end of str1, and returns str1. For example: printf( "Enter your name: " ); scanf( "%s", name ); title = strcat( name, " the Great" ); printf( "Hello, %s\n", title );

strchr

2010-08-03T15:24:56-07:00

strchr Syntax: #include char *strchr( const char *str, int ch ); The function strchr() returns a pointer to the first occurence of ch in str, or NULL if ch is not found. Related Topics: strcat, strcmp, strcpy, strlen, strncat, strncmp, strncpy, strpbrk, strspn, strstr, strtok

strcmp

2008-10-14T15:42:02-07:00

strcmp Syntax: #include int strcmp( const char *str1, const char *str2 ); The function strcmp() compares str1 and str2, then returns: Return value Explanationless than 0 str1 is less than str2equal to 0 str1 is equal to str2greater than 0 str1 is greater than str2 For example:

strcoll

2008-12-19T10:53:00-07:00

strcoll Syntax: #include int strcoll( const char *str1, const char *str2 ); The strcoll function compares str1 and str2, much like strcmp. However, strcoll performs the comparison using the locale specified by the setlocale function.

strcpy

2010-08-03T15:14:49-07:00

strcpy Syntax: #include char *strcpy( char *dest, const char *src ); The strcpy() function copies characters in the string src to the string dest, including the null termination. The return value is dest. Note that strcpy() does not perform bounds checking, and thus risks overrunning from or to. For a similar (and safer) function that includes bounds checking, see strncpy().

strcspn

2008-10-14T15:42:03-07:00

strcspn Syntax: #include size_t strcspn( const char *str1, const char *str2 ); The function strcspn() returns the index of the first character in str1 that matches any of the characters in str2. Related Topics: strpbrk, strrchr, strstr, strtok

strerror

2009-09-02T19:17:35-07:00

strerror Syntax: #include const char *strerror( int num ); The function strerror() returns an implementation defined string corresponding to num. Related Topics: perror

strlcat

2009-01-28T08:05:58-07:00

strlcat Warning: Non-standard function! Syntax: #include // On BSD or compatible systems size_t strlcat( char *dst, const char *src, size_t siz); An attempt of the BSD people to “fix” strncat. There is a reason this function is not in any ISO standard. It is not a clear improvement over strncat, but rather an “overload” with different tradeoffs.

strlcpy

2010-08-18T00:47:59-07:00

strlcpy Warning: Non-standard function! Syntax: #include // On BSD or compatible systems size_t strlcpy( char *dst, const char *src, size_t siz); An attempt of the BSD people to “fix” strncpy. There is a reason this function is not in any ISO standard. See explanation after the description.

strlen

2009-05-21T02:20:49-07:00

strlen Syntax: #include size_t strlen( char *str ); The strlen() function returns the length of str (determined by the number of characters before null termination). Str may not be null. Related Topics: memcpy, strchr, strcmp, strncmp

strncat

2009-01-28T08:11:04-07:00

strncat Syntax: #include char *strncat( char *str1, const char *str2, size_t count ); The function strncat() concatenates at most count characters of str2 onto str1, adding a null termination. The resulting string is returned.

strncmp

2009-06-09T04:16:16-07:00

strncmp Syntax: #include int strncmp( const char *str1, const char *str2, size_t count ); The strncmp() function compares at most count characters of str1 and str2. The return value is as follows: Return value Explanationless than 0 str1 is less than str2equal to 0 str1 is equal to str2greater than 0 str1 is greater than str2 If there are less than count characters in either string, then the comparison will stop after the first null termination is encountered.

strncpy

2010-01-12T22:53:49-07:00

strncpy Syntax: #include char *strncpy( char *to, const char *from, size_t count ); namespace std { using ::strncpy; } The strncpy function copies at most count characters of from to the string to. If from has less than count characters, the remainder is padded with '\0' characters. The return value is the resulting string.

strpbrk

2009-12-05T15:14:19-07:00

strpbrk Syntax: #include char* strpbrk( const char* str1, const char* str2 ); The function strpbrk() returns a pointer to the first occurrence in str1 of any character in str2, or NULL if no such characters are present. Related Topics: (C++ Algorithms) find_first_of, strchr, strcspn, strrchr, strspn, strstr, strtok

strrchr

2008-10-14T15:42:03-07:00

strrchr Syntax: #include char *strrchr( const char *str, int ch ); The function strrchr() returns a pointer to the last occurrence of ch in str, or NULL if no match is found. Related Topics: strcspn, strpbrk, strspn, strstr, strtok

strspn

2008-10-14T15:42:03-07:00

strspn Syntax: #include size_t strspn( const char *str1, const char *str2 ); The strspn() function returns the index of the first character in str1 that doesn't match any character in str2. Related Topics: strchr, strpbrk, strrchr, strstr, strtok

strstr

2010-03-08T05:15:23-07:00

strstr Syntax: #include const char *strstr( const char *str1, const char *str2 ); char *strstr( char *str1, const char *str2 ); The function strstr returns a pointer to the first occurrence of str2 in str1, or NULL if no match is found. If the length of str2 is zero, then strstr will simply return str1.

strtod

2008-10-14T15:42:03-07:00

strtod Syntax: #include double strtod( const char *start, char **end ); The function strtod() returns whatever it encounters first in start as a double. end is set to point at whatever is left in start after that double. If overflow occurs, strtod() returns either HUGE_VAL or -HUGE_VAL.

strtok

2010-08-03T15:30:09-07:00

strtok Syntax: #include char *strtok( char *str1, const char *str2 ); The strtok function returns a pointer to the next “token” in str1, where str2 contains the delimiters that determine the token. strtok returns NULL if no token is found.

strtol

2009-04-17T05:03:48-07:00

strtol Syntax: #include long strtol( const char *start, char **end, int base ); The strtol() function returns whatever it encounters first in start as a long, doing the conversion to base if necessary. end is set to point to whatever is left in start after the long. If the result can not be represented by a long, then strtol() returns either LONG_MAX or LONG_MIN. Zero is returned upon error.

strtoul

2009-03-02T18:02:37-07:00

strtoul Syntax: #include unsigned long strtoul( const char *start, char **end, int base ); The function strtoul() behaves exactly like strtol(), except that it returns an unsigned long rather than a mere long, and that it returns ULONG_MAX on overflow.

c:string:strtrm

2008-12-13T01:08:01-07:00

int lfttrm(char* str) { int len = 0; char* tmp; len = (int)strlen(str); if(0 == len) return len; tmp = str; while(len > 0){ if(0x20 == *tmp){ tmp++; len--; } else if(len > 1){ if((char)0x81 == *tmp && (char)0x40 == *(tmp+1)){ tmp += 2; len -= 2; } else break; } else break; } strcpy(str, tmp); return len; } int rgttrm(char* str) {

strxfrm

2008-10-14T15:42:03-07:00

strxfrm Syntax: #include size_t strxfrm( char *str1, const char *str2, size_t num ); The strxfrm() function manipulates the first num characters of str2 and stores them in str1. The result is such that if a strcoll() is performed on str1 and the old str2, you will get the same result as with a strcmp().

tolower

2008-10-14T15:42:03-07:00

tolower Syntax: #include int tolower( int ch ); The function tolower() returns the lowercase version of the character ch. Related Topics: isupper, toupper

toupper

2009-12-29T06:42:56-07:00

toupper Syntax: #include int toupper( int ch ); The toupper function returns the uppercase version of the character ch. Related Topics: tolower