String processing functions in Standard C Language

Refference: http://blog.chinaunix.net/u1/56388/showart_2059483.html

Function Name: stpcpy <br/> function: copy a string to another <br/> usage: char * stpcpy (char * Destin, char * Source ); <br/> program example: <br/> # include <stdio. h> <br/> # include <string. h> <br/> int main (void) <br/>{< br/> char string [10]; <br/> char * str1 = "abcdefghi "; <br/> stpcpy (string, str1); <br/> printf ("% s/n", string); <br/> return 0; <br/>}</P> <p> function name: strcat <br/> function: String concatenation function <br/> usage: char * strcat (char * Destin, char * Source); <br/> program example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char destination [25]; <br/> char * blank = "", * c = "C ++", * Borland = "Borland"; <br/> strcpy (destination, Borland); <br/> strcat (destination, blank ); <br/> strcat (destination, c); <br/> printf ("% s/n", destination); <br/> return 0; <br/>}</P> <p> function name: strchr <br/> functions: find the first match of a given character in a string/<br/> usage: char * strchr (char * STR, char C); <br/> example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char string [15]; <br/> char * PTR, c = 'R '; <br/> strcpy (string, "This is a string"); <br/> PTR = strchr (string, c); <br/> If (PTR) <br/> printf ("the character % C is at position: % d/N", C, PTR-string ); <br/> else <br/> printf ("the character was not found/N"); <br/> return 0; <br/>}</P> <p> function name: strcmp <br/> function: String comparison <br/> method: int strcmp (char * str1, char * str2); <br/> View ASIC code, str1> str2, return value> 0; two strings are equal, return 0 <br/> example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char * buf1 = "AAA", * buf2 = "BBB ", * buf3 = "CCC"; <br/> int PTR; <br/> PTR = strcmp (buf2, buf1); <br/> If (PTR> 0) <br/> printf ("Buffer 2 is greater than buffer 1/N "); <br/> else <br/> printf ("Buffer 2 is less than buffer 1/N"); <br/> PTR = strcmp (buf2, buf3 ); <br/> If (PTR> 0) <br/> printf ("Buffer 2 is greater than buffer 3/N "); <br/> else <br/> printf ("Buffer 2 is less than buffer 3/N"); <br/> return 0; <br/>}</P> <p> function name: strncmpi <br/> function: compares a part of a string with another one, case-insensitive <br/> usage: int strncmpi (char * str1, char * str2, unsigned maxlen); <br/> example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char * buf1 = "BBB", * buf2 = "BBB "; <br/> int PTR; <br/> PTR = strcmpi (buf2, buf1); <br/> If (PTR> 0) <br/> printf ("Buffer 2 is greater than buffer 1/N"); <br/> If (PTR <0) <br/> printf ("Buffer 2 is less than buffer 1/N"); <br/> If (PTR = 0) <br/> printf ("Buffer 2 equals buffer 1/N"); <br/> return 0; <br/>}</P> <p> Function Name: strcpy <br/> function: String Copy <br/> usage: char * strcpy (char * str1, char * str2); <br/> example: <br/> # include <stdio. h> <br/> # include <string. h> <br/> int main (void) <br/>{< br/> char string [10]; <br/> char * str1 = "abcdefghi "; <br/> strcpy (string, str1); <br/> printf ("% s/n", string); <br/> return 0; <br/>}</P> <p> function name: strcspn <br/> functions: find the content segment of the first given character set in the string <br/> usage: int strcspn (char * str1, char * str2); <br/> example: <br/> # include <stdio. h> <br/> # include <string. h> <br/> # include <alloc. h> <br/> int main (void) <br/>{< br/> char * string1 = "1234567890"; <br/> char * string2 = "747dc8 "; <br/> int length; <br/> length = strcspn (string1, string2); <br/> printf ("character where strings intersect is at position % d/N ", length); <br/> return 0; <br/>}</P> <p> function name: strdup <br/> function: copy the string to the new location <br/> method: char * strdup (char * Str); <br/> example: <br/> # include <stdio. h> <br/> # include <string. h> <br/> # include <alloc. h> <br/> int main (void) <br/>{< br/> char * dup_str, * string = "ABCDE "; <br/> dup_str = strdup (string); <br/> printf ("% s/n", dup_str); <br/> free (dup_str ); <br/> return 0; <br/>}</P> <p> function name: stricmp <br/> functions: comparison of two strings in upper and lower case insensitive mode <br/> Syntax: int stricmp (char * str1, char * str2); <br/> example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char * buf1 = "BBB", * buf2 = "BBB "; <br/> int PTR; <br/> PTR = stricmp (buf2, buf1); <br/> If (PTR> 0) <br/> printf ("Buffer 2 is greater than buffer 1/N"); <br/> If (PTR <0) <br/> printf ("Buffer 2 is less than buffer 1/N"); <br/> If (PTR = 0) <br/> printf ("Buffer 2 equals buffer 1/N"); <br/> return 0; <br/>}</P> <p> Function Name: strerror <br/> function: returns a pointer to the error message string <br/> usage: char * strerror (INT errnum); <br/> example: <br/> # include <stdio. h> <br/> # include <errno. h> <br/> int main (void) <br/>{< br/> char * buffer; <br/> buffer = strerror (errno ); <br/> printf ("error: % s/n", buffer); <br/> return 0; <br/>}</P> <p> Function Name: strcmpi <br/> function: compares a string with another string, regardless of case. <br/> usage: int strcmpi (char * str1, char * str2 ); <br/> program example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char * buf1 = "BBB", * buf2 = "BBB "; <br/> int PTR; <br/> PTR = strcmpi (buf2, buf1); <br/> If (PTR> 0) <br/> printf ("Buffer 2 is greater than buffer 1/N"); <br/> If (PTR <0) <br/> printf ("Buffer 2 is less than buffer 1/N"); <br/> If (PTR = 0) <br/> printf ("Buffer 2 equals buffer 1/N"); <br/> return 0; <br/>}</P> <p> Function Name: strncmp <br/> function: String comparison <br/> usage: int strncmp (char * str1, char * str2, int maxlen); <br/> example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char * buf1 = "aaabbb", * buf2 = "bbbccc ", * buf3 = "CCC"; <br/> int PTR; <br/> PTR = strncmp (buf2, buf1, 3); <br/> If (PTR> 0) <br/> printf ("Buffer 2 is greater than buffer 1/N "); <br/> else <br/> printf ("Buffer 2 is less than buffer 1/N"); <br/> PTR = strncmp (buf2, buf3, 3 ); <br/> If (PTR> 0) <br/> printf ("Buffer 2 is greater than buffer 3/N "); <br/> else <br/> printf ("Buffer 2 is less than buffer 3/N"); <br/> return (0 ); <br/>}</P> <p> function name: strncmpi <br/> function: compares a part of a string with a part of another string, case-insensitive <br/> usage: int strncmpi (char * str1, char * str2); <br/> program example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char * buf1 = "bbbccc", * buf2 = "bbbccc "; <br/> int PTR; <br/> PTR = strncmpi (buf2, buf1, 3); <br/> If (PTR> 0) <br/> printf ("Buffer 2 is greater than buffer 1/N"); <br/> If (PTR <0) <br/> printf ("Buffer 2 is less than buffer 1/N"); <br/> If (PTR = 0) <br/> printf ("Buffer 2 equals buffer 1/N"); <br/> return 0; <br/>}</P> <p> Function Name: strncpy <br/> function: String Copy <br/> usage: char * strncpy (char * Destin, char * Source, int maxlen); <br/> example: <br/> # include <stdio. h> <br/> # include <string. h> <br/> int main (void) <br/>{< br/> char string [10]; <br/> char * str1 = "abcdefghi "; <br/> strncpy (string, str1, 3); <br/> string [3] = '/0'; <br/> printf ("% s/n ", string); <br/> return 0; <br/>}</P> <p> function name: strnicmp <br/> functions: use case-insensitive comparison of two strings <br/>: int strnicmp (char * str1, char * str2, unsigned maxlen); <br/> example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char * buf1 = "bbbccc", * buf2 = "bbbccc "; <br/> int PTR; <br/> PTR = strnicmp (buf2, buf1, 3); <br/> If (PTR> 0) <br/> printf ("Buffer 2 is greater than buffer 1/N"); <br/> If (PTR <0) <br/> printf ("Buffer 2 is less than buffer 1/N"); <br/> If (PTR = 0) <br/> printf ("Buffer 2 equals buffer 1/N"); <br/> return 0; <br/>}</P> <p> Function Name: strnset <br/> function: Set all characters in a string to a specified character <br/> usage: char * strnset (char * STR, char CH, unsigned N); <br/> program example: <br/> # include <stdio. h> <br/> # include <string. h> <br/> int main (void) <br/>{< br/> char * string = "abcdefghijklmnopqrstuvwxyz"; <br/> char letter = 'X '; <br/> printf ("string before strnset: % s/n", string); <br/> strnset (string, letter, 13 ); <br/> printf ("string after strnset: % s/n", string); <br/> return 0; <br/>}</P> <p> function name: strpbrk <br/> function: searches for characters in a given character set in a string. <br/> usage: char * strpbrk (char * str1, char * str2); <br/> program example: <br/> # include <stdio. h> <br/> # include <string. h> <br/> int main (void) <br/>{< br/> char * string1 = "abcdefghijklmnopqrstuvwxyz"; <br/> char * string2 = "onm "; <br/> char * PTR; <br/> PTR = strpbrk (string1, string2); <br/> If (PTR) <br/> printf ("strpbrk found first character: % C/N", * PTR ); <br/> else <br/> printf ("strpbrk didn't find character in set/N"); <br/> return 0; <br/>}</P> <p> function name: strrchr <br/> function: Find the last occurrence of a specified character in a string <br/> usage: char * strrchr (char * STR, char C); <br/> program example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char string [15]; <br/> char * PTR, c = 'R '; <br/> strcpy (string, "This is a string"); <br/> PTR = strrchr (string, c); <br/> If (PTR) <br/> printf ("the character % C is at position: % d/N", C, PTR-string ); <br/> else <br/> printf ("the character was not found/N"); <br/> return 0; <br/>}</P> <p> function name: strrev <br/> function: String inversion <br/> usage: char * strrev (char * Str); <br/> program example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char * Forward = "string"; <br/> printf ("before strrev (): % s/n ", forward); <br/> strrev (forward); <br/> printf (" after strrev (): % s/n ", forward ); <br/> return 0; <br/>}</P> <p> function name: strset <br/> functions: set all characters in a string to a specified character <br/> usage: char * strset (char * STR, char C); <br/> example: <br/> # include <stdio. h> <br/> # include <string. h> <br/> int main (void) <br/>{< br/> char string [10] = "123456789 "; <br/> char symbol = 'C'; <br/> printf ("before strset (): % s/n", string); <br/> strset (string, symbol); <br/> printf ("after strset (): % s/n", string); <br/> return 0; <br/>}</P> <p> function name: strspn <br/> functions: find the first occurrence of a subset of a specified character set in a string <br/> usage: int strspn (char * str1, char * str2); <br/> example: <br/> # include <stdio. h> <br/> # include <string. h> <br/> # include <alloc. h> <br/> int main (void) <br/>{< br/> char * string1 = "1234567890"; <br/> char * string2 = "123dc8 "; <br/> int length; <br/> length = strspn (string1, string2); <br/> printf ("character where strings differ is at position % d/N ", length); <br/> return 0; <br/>}</P> <p> function name: strstr <br/> functions: find the first occurrence of a specified string in the string <br/> usage: char * strstr (char * str1, char * str2); <br/> example: <br/> # include <stdio. h> <br/> # include <string. h> <br/> int main (void) <br/>{< br/> char * str1 = "Borland International", * str2 = "nation", * PTR; <br/> PTR = strstr (str1, str2); <br/> printf ("the substring is: % s/n", PTR); <br/> return 0; <br/>}</P> <p> function name: strtodd <br/> function: convert a string to a double value. <br/> usage: double strtodd (char * STR, char ** endptr); <br/> program example: <br/> # include <stdio. h> <br/> # include <stdlib. h> <br/> int main (void) <br/>{< br/> char input [80], * endptr; <br/> double value; <br/> printf ("enter a floating point number:"); <br/> gets (input); <br/> value = strtodd (input, & endptr ); <br/> printf ("the string is % s the number is % lf/N", input, value); <br/> return 0; <br/>}</P> <p> function name: strtok <br/> functions: find words separated by the delimiters specified in the second string <br/> usage: char * strtok (char * str1, char * str2 ); <br/> program example: <br/> # include <string. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char input [16] = "ABC, D"; <br/> char * P; <br/>/* strtok places a null Terminator <br/> in front of the token, if found */<br/> P = strtok (input ,","); <br/> If (p) printf ("% s/n", P ); <br/>/* a second call to strtok using a null <br/> as the first parameter returns a pointer <br/> to the character following the token */<br/> P = strtok (null, ","); <br/> If (p) printf ("% s/n", P); <br/> return 0; <br/>}</P> <p> function name: strtol <br/> function: converts a string to a long integer. <br/> usage: long strtol (char * STR, char ** endptr, int base); <br/> program example: <br/> # include <stdlib. h> <br/> # include <stdio. h> <br/> int main (void) <br/>{< br/> char * string = "87654321", * endptr; <br/> long lnumber; <br/>/* strtol converts string to long integer */<br/> lnumber = strtol (string, & endptr, 10 ); <br/> printf ("string = % s long = % LD/N", String, lnumber); <br/> return 0; <br/>}</P> <p> function name: strupr <br/> function: converts lowercase letters in a string to uppercase letters. <br/> usage: char * strupr (char * Str); <br/> example: <br/> # include <stdio. h> <br/> # include <string. h> <br/> int main (void) <br/>{< br/> char * string = "abcdefghijklmnopqrstuvwxyz", * PTR; <br/>/* converts string to upper case characters */<br/> PTR = strupr (string); <br/> printf ("% s/n ", PTR); <br/> return 0; <br/>}</P> <p> function name: swab <br/> functions: byte switching <br/> usage: void swab (char * From, char * To, int nbytes); <br/> example: <br/> # include <stdlib. h> <br/> # include <stdio. h> <br/> # include <string. h> <br/> char source [15] = "rfna koblrna D"; <br/> char target [15]; <br/> int main (void) <br/>{< br/> swab (source, target, strlen (source); <br/> printf ("this is target: % s/n ", target); <br/> return 0; <br/>}