Part IV • Documenting the Differences
strpbrk()
Header: string.h
Syntax: char * strpbrk(const char * szString, const char * szCharacters);
Description: Finds the first occurrence of any character from szCharacters found in szString.
Parameters: szString—Pointer to a string to search.
szCharacters—Pointer to a string containing characters to search for.
Returns: |
Pointer to the first character found in szString that is in |
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szCharacters. |
Example: |
char |
szString1[] = |
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{“Now is |
all the time for all good men”}; |
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char |
* |
pChars; |
pChars = strpbrk(szString1, “fzxy”);
if (pChars)
{
printf(“found at ‘%s’\n”, pChars);
}
/* Will print found at ‘for all good men’ */
strrchr()
Header: string.h
Syntax: char * strrchr(const char * szString, int chChar);
Description: Finds the last occurrence of chChar found in szString.
Parameters: szString—Pointer to a string to search.
chChar—Character to search for.
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ANSI C’s Library Function |
C C C |
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14C |
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C C C |
Returns: |
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C C |
Pointer to the last occurrence of chChar found in szString. |
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Example: |
char |
szString1[] = |
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{“Now is all the time for all good men”}; |
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char |
* pChars; |
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pChars = strrchr(szString1, ‘a’); |
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if (pChars) |
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{ |
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printf(“found at ‘%s’\n”, |
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pChars); |
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} |
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/* Will print found at ‘all good men’ */ |
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strspn() |
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Header: |
string.h |
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Syntax: |
size_t strspn(const char * szString, const char * |
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szChars); |
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Description: |
Returns the length of the initial string that contains characters |
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found in szChars. |
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Parameters: |
szString—Pointer to a string to be searched. |
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szChars—String containing characters that must be contained. |
Returns: |
Length of the initial string that contains only characters from |
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szChars, up to the length of szString. |
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Example: |
char |
szString[100] = |
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{“Now is the time for all good men.”}; |
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char |
szOutput[100]; |
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memset(szOutput, 0, sizeof(szOutput));
strncpy(szOutput, szString, strspn(szString, “woN si teh”));
Part IV • Documenting the Differences
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printf(“%s”, |
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szOutput); |
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/* will print Now is the ti */ |
Note: |
Also see strcspn(). |
strstr()
Header: |
string.h |
Syntax: |
char * strstr(const char * szString, const char * |
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szCharacters); |
Description: |
Finds the first occurrence of szCharacters in szSting. |
Parameters: |
szString—Pointer to the string to search. |
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szCharacters—Pointer to the characters to search for. |
Returns: |
Pointer to the point where the characters were found. |
Example: |
char szString[100] = |
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{“Now is the time for all good men.”}; |
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printf(“‘%s’”, strstr(szString, “me”)); |
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/* will print ‘me for all good men.’ */ |
Note: |
Basically a search for a substring in a string function. |
strtod()
Header: |
stdlib.h |
Syntax: |
double strtod(const char * szString, |
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char ** pEnd); |
Description: |
Converts the string to a floating point number, stopping when an |
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invalid character has been reached. The stopping point is stored |
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in the variable pointed to by pEnd if pEnd is not NULL. |
Parameters: |
szString—Pointer to the string to convert. |
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pEnd—Pointer to a string pointer. |
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ANSI C’s Library Function |
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Returns: |
The floating point number converted. |
Example: |
double |
dValue; |
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char |
szString[100] = |
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{“123.34 Now is the time for all good men.”}; |
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char |
* pEnd; |
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dValue = strtod(szString, &pEnd); |
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printf(“Converted %f stopped at ‘%s’\n”, |
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dValue, |
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pEnd); |
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/* |
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* Prints: Converted 123.340000 stopped at |
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‘ Now is the time for all good men.’ |
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*/ |
Note: |
See strtol(). |
strtok()
Header: string.h
Syntax: char * strtok(char * szString, const char * szTokenSep);
Description: Breaks the string pointed to by szString into tokens, when each token is separated by one (or more) of the characters found in
szTokenSep.
Parameters: szString—Pointer to a string to break into tokens. This string will be modified, so use a copy if necessary.
szTokenSep—Pointer to a string of token separators.
Returns: |
Pointer to a token from szString. |
Example: |
char |
szString[100] = |
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{“Now is |
the time for all good men.”}; |
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char |
szTokens[] = {“ .”}; |
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char |
* |
pToken; |
Part IV • Documenting the Differences
printf(“‘%s’\n”, szString);
pToken = strtok(szString, szTokens);
do
{
printf(“Token ‘%s’\n”, pToken);
} while (pToken = strtok(NULL, szTokens));
printf(“‘%s’\n”, szString);
/*
*Prints:
*‘Now is the time for all good men.’
*Token ‘Now’
*Token ‘is’
*Token ‘the’
*Token ‘time’
*Token ‘for’
*Token ‘all’
*Token ‘good’
*Token ‘men’
*‘Now’
*/
Note: Don’t forget that this function modifies the string passed.
strtol()
Header: stdlib.h
Syntax: long strtol(const char * szString, char ** pEnd,
int nBase);
Description: Converts the string to a long integer number, stopping when an invalid character has been reached. The stopping point is stored in the variable pointed to by pEnd if pEnd is not NULL. The parameter nBase determines what base is used and must be either 0 or 2 through 36. If nBase is zero, then the base of the
Part IV • Documenting the Differences
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either 0 or 2 through 36. If nBase is zero, then the base of the |
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number is determined from the number’s format; if the number |
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starts with 0x or 0X, then it is base 16; if it starts with a zero, |
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then base 8 is assumed; otherwise it is decimal based. |
Parameters: |
szString—Pointer to the string to convert. |
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pEnd—Pointer to a string pointer. |
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nBase—Base of the number to be converted. |
Returns: |
The long integer converted. |
Example: |
unsigned long lValue; |
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char |
szString[100] = |
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{“123.34 Now is the time for all good men.”}; |
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char |
* pEnd; |
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lValue = strtoul(szString, &pEnd, 0); |
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printf(“Converted %ld stopped at ‘%s’\n”, |
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lValue, |
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pEnd); |
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/* |
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* Prints: Converted 123 stopped at ‘.34 Now is the time |
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for all good men.’ |
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*/ |
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Note: |
See strtol(). |
strxfrm()
Header: |
string.h |
Syntax: |
size_t strxfrm (char * szDestination, const char * |
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szSource, size_t nLength); |
Description: |
Copies the string pointed to by szSource to the buffer pointed to |
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by szDestination, using the collating sequence set by setlocale |
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(). The function is identical to strncpy() when the locale is “C”, |
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ANSI C’s Library Function |
C C C |
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14C |
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C C C |
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C C |
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except thestring is not paddedwith NULL characters when szSource |
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is shorter than nLength. |
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Parameters: |
szDestination—Pointer to a buffer where szSource will be |
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copied to. |
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szSource—Pointer to a string to copy and convert. |
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nLength—Maximum number of characters to copy and convert. |
Returns: |
Length of the converted string. |
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Example: |
char |
szSource[100] = |
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{“Now is the time for all good men.”}; |
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char |
szDestination[100]; |
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strxfrm(szDestination, szSource, strlen(szSource));
printf(“Converted \n’%s’ \nto \n’%s’\n”, szSource,
szDestination);
/*
*Prints:
*Converted
*‘Now is the time for all good men.’
*to
*‘Now is the time for all good men.’
*/
system()
Header: process.h & stdlib.h
Syntax: int system(const char * szCommand);
Description: Passes the string pointed to by szCommand to the operating system’s command processor.
Part IV • Documenting the Differences
Parameters: |
szCommand—Pointer to a string containing an operating system |
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command, or NULL to determine if there is a command processor. |
Returns: |
If szCommand is NULL, non-zero if there is a command processor, |
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otherwise a zero value. If szCommand is not NULL, then zero if there |
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was no error, or a non-zero value if the command processor |
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couldn’t be loaded. |
Example: |
/* Check for command processor, and do a dir command if |
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present */ |
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if (system(NULL)) |
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{ |
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system(“dir *.*”); |
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} |
Note: |
Most operating systems have a loadable command processor. |
tan()
Header: |
math.h |
Syntax: |
double tan(double dValue); |
Description: |
Returns the tangent of dValue, measured in radians. |
Parameters: |
dValue—Value for which tangent is desired. |
Returns: |
The tangent of dValue. |
Example: |
double dResult; |
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dResult = tan(1.5); |
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/* dResult will be 14.10142 */ |
Note: |
Also see tanh(). |
tanh()
Header: math.h
Syntax: double tanh(double dValue);
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ANSI C’s Library Function |
C C C |
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14C |
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C C C |
Description: |
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C C |
Returns the hyperbolic tangent of dValue, measured in radians. |
Parameters: |
dValue—Value for which hyperbolic tangent is desired. |
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Returns: |
The hyperbolic tangent of dValue. |
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Example: |
double |
dResult; |
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dResult = tanh(1.5); |
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/* dResult will be 0.905148 */ |
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Note: |
Also see tan(). |
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time() |
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Header: |
time.h |
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Syntax: |
time_t time(time_t * TimeValue); |
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Description: |
Returns the current calendar time encoded into a time_t type. |
Parameters: |
TimeValue—Pointer to a type time_t, which if not NULL, will also |
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receive the time. |
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Returns: |
The current time. |
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Example: |
char |
szBuffer[100]; |
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time_t |
OurTime; |
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OurTime = time(NULL);
strftime(szBuffer, sizeof(szBuffer), “Today is %A %B %d, %Y”,
localtime(&OurTime));
printf(“%s\n”, szBuffer);
/* Will print Today is Saturday June 27, 1992 */
Note: Also see strftime() and ctime(). The function time()’s parameter is often NULL as shown in the preceding example.
