C ++ strcmp usage

Function Name: strcmp function: String comparison method: int strcmp (char * str1, char * str2); view ASIC code, str1> str2, return value> 0; two strings are equal, return 0 program example: # include <string. h> # include <stdio. h> int main (void) {char * buf1 = "AAA", * buf2 = "BBB", * buf3 = "CCC"; int PTR; PTR = strcmp (buf2, buf1); If (PTR> 0) printf ("Buffer 2 is greater than buffer 1N"); else printf ("Buffer 2 is less than buffer 1N "); PTR = strcmp (buf2, buf3); If (PTR> 0) printf ("buffe R 2 is greater than buffer 3N "); else printf (" Buffer 2 is less than buffer 3N "); Return 0 ;} /* next, I will give you another related function application */function name: stpcpy function: copy a string to another method: char * stpcpy (char * Destin, char * Source ); program example: # include <stdio. h> # include <string. h> int main (void) {char string [10]; char * str1 = "abcdefghi"; stpcpy (string, str1); printf ("% Sn", string ); return 0;} function name: strcat function: String concatenation function usage: char * strcat (char * dest In, char * Source); program example: # include <string. h> # include <stdio. h> int main (void) {char destination [25]; char * blank = "", * c = "C ++", * Borland = "Borland "; strcpy (destination, Borland); strcat (destination, blank); strcat (destination, c); printf ("% Sn", destination); Return 0;} function name: strchr function: Find the first matching character in a string using the method: char * strchr (char * STR, char C); example: # include <string. h> # include <stdio. h> int Main (void) {char string [15]; char * PTR, c = 'R'; strcpy (string, "This is a string"); PTR = strchr (string, c); If (PTR) printf ("the character % C is at position: % DN", C, PTR-string ); else printf ("the character was not foundn"); Return 0;} function name: strncmpi function: Compares one part of a string with another, regardless of Case sensitivity: int strncmpi (char * str1, char * str2, unsigned maxlen); example: # include <string. h> # include <stdio. h> int main (void) {Char * buf1 = "BBB", * buf2 = "BBB"; int PTR; PTR = strcmpi (buf2, buf1); If (PTR> 0) printf ("Buffer 2 is greater than buffer 1N"); If (PTR <0) printf ("Buffer 2 is less than buffer 1N"); If (PTR = 0) printf ("Buffer 2 equals buffer 1N"); Return 0;} function name: strcpy function: string copy method: char * strcpy (char * str1, char * str2 ); program example: # include <stdio. h> # include <string. h> int main (void) {char string [10]; char * s Tr1 = "abcdefghi"; strcpy (string, str1); printf ("% Sn", string); Return 0;} function name: strcsps' functions: the method used to search for the content of the first given character set in the string: int strcspn (char * str1, char * str2); example: # include <stdio. h> # include <string. h> # include <alloc. h> int main (void) {char * string1 = "1234567890"; char * string2 = "747dc8"; int length; length = strcspns (string1, string2 ); printf ("character where strings intersect is at position % DN ", Length); Return 0;} function name: strdup function: copy the string to the new position using the method: char * strdup (char * Str); example: # include <stdio. h> # include <string. h> # include <alloc. h> int main (void) {char * dup_str, * string = "ABCDE"; dup_str = strdup (string); printf ("% Sn", dup_str ); free (dup_str); Return 0;} function name: stricmp function: Compares two strings in uppercase/lowercase insensitive mode: int stricmp (char * str1, char * str2 ); program example: # include <string. h> # include <stdio. h> int main (voi D) {char * buf1 = "BBB", * buf2 = "BBB"; int PTR; PTR = stricmp (buf2, buf1); If (PTR> 0) printf ("Buffer 2 is greater than buffer 1N"); If (PTR <0) printf ("Buffer 2 is less than buffer 1N"); If (PTR = 0) printf ("Buffer 2 equals buffer 1N"); Return 0;} function name: strerror function: returns a pointer to the error message string. Usage: char * strerror (INT errnum ); program example: # include <stdio. h> # include <errno. h> int main (void) {char * buffer; Buffer = Strerror (errno); printf ("error: % Sn", buffer); Return 0;} function name: strcmpi function: compare one string with another, case-insensitive method: int strcmpi (char * str1, char * str2); example: # include <string. h> # include <stdio. h> int main (void) {char * buf1 = "BBB", * buf2 = "BBB"; int PTR; PTR = strcmpi (buf2, buf1 ); if (PTR> 0) printf ("Buffer 2 is greater than buffer 1N"); If (PTR <0) printf ("Buffer 2 is less than buffer 1N "); if (PTR = 0) Printf ("Buffer 2 equals buffer 1N"); Return 0;} function name: strncmp function: String comparison method: int strncmp (char * str1, char * str2, int maxlen); program example: # include <string. h> # include <stdio. h> int main (void) {char * buf1 = "aaabbb", * buf2 = "bbbccc", * buf3 = "CCC"; int PTR; PTR = strncmp (buf2, buf1, 3); If (PTR> 0) printf ("Buffer 2 is greater than buffer 1N"); else printf ("Buffer 2 is less than buffer 1N "); PTR = strncmp (B Uf2, buf3, 3); If (PTR> 0) printf ("Buffer 2 is greater than buffer 3N"); else printf ("Buffer 2 is less than buffer 3N "); return (0);} function name: strncmpi function: compares a part of the string with a part of the other string, regardless of case: int strncmpi (char * str1, char * str2); program example: # include <string. h> # include <stdio. h> int main (void) {char * buf1 = "bbbccc", * buf2 = "bbbccc"; int PTR; PTR = strncmpi (buf2, buf1, 3 ); if (PTR> 0) printf ("Buffer 2 is greater Than buffer 1N "); If (PTR <0) printf (" Buffer 2 is less than buffer 1N "); If (PTR = 0) printf ("Buffer 2 equals buffer 1N"); Return 0;} function name: strncpy function: string copy method: char * strncpy (char * Destin, char * source, int maxlen); program example: # include <stdio. h> # include <string. h> int main (void) {char string [10]; char * str1 = "abcdefghi"; strncpy (string, str1, 3); string [3] = ''; printf ("% Sn", string); Return 0;} letter Parameter: strnicmp function: Compares two strings in case-insensitive mode: int strnicmp (char * str1, char * str2, unsigned maxlen); example: # include <string. h> # include <stdio. h> int main (void) {char * buf1 = "bbbccc", * buf2 = "bbbccc"; int PTR; PTR = strnicmp (buf2, buf1, 3 ); if (PTR> 0) printf ("Buffer 2 is greater than buffer 1N"); If (PTR <0) printf ("Buffer 2 is less than buffer 1N "); if (PTR = 0) printf ("Buffer 2 equals buffer 1N"); R Eturn 0;} function name: strnset function: Set all characters in a string to a specified character. Usage: char * strnset (char * STR, char CH, unsigned N ); program example: # include <stdio. h> # include <string. h> int main (void) {char * string = "abcdefghijklmnopqrstuvwxyz"; char letter = 'X'; printf ("string before strnset: % Sn", string ); strnset (string, letter, 13); printf ("string after strnset: % Sn", string); Return 0;} function name: strpbrk function: character usage in the given character set in a string: char * St Rpbrk (char * str1, char * str2); example: # include <stdio. h> # include <string. h> int main (void) {char * string1 = "abcdefghijklmnopqrstuvwxyz"; char * string2 = "onm"; char * PTR; PTR = strpbrk (string1, string2 ); if (PTR) printf ("strpbrk found first character: % CN", * PTR); else printf ("strpbrk didn't find character in setn"); Return 0 ;} function Name: strrchr function: used to find the last occurrence of a specified character in a string: char * strrchr (char * STR, char C); program example: # include <string. h> # include <stdio. h> int main (void) {char string [15]; char * PTR, c = 'R'; strcpy (string, "This is a string "); PTR = strrchr (string, c); If (PTR) printf ("the character % C is at position: % DN", C, PTR-string ); else printf ("the character was not foundn"); Return 0;} function name: strrev function: String inversion method: char * strrev (char * Str); example: # include <string. h> # include <stdio. h> int main (voi D) {char * Forward = "string"; printf ("before strrev (): % Sn", forward); strrev (forward); printf ("after strrev (): % Sn ", forward); Return 0;} function name: strset function: Set all characters in a string to the specified character. Usage: char * strset (char * STR, char C); program example: # include <stdio. h> # include <string. h> int main (void) {char string [10] = "123456789"; char symbol = 'C'; printf ("before strset (): % Sn", string ); strset (string, symbol); printf ("afte R strset (): % Sn ", string); Return 0;} function name: strspn function: Find the first appearance of a subset of a specified character set in a string. Usage: int strspn (char * str1, char * str2); example: # include <stdio. h> # include <string. h> # include <alloc. h> int main (void) {char * string1 = "1234567890"; char * string2 = "123dc8"; int length; length = strspns (string1, string2 ); printf ("character where strings differ is at position % DN", length); Return 0;} function name: strstr function: Check the string Method used to find the first occurrence of a specified string: char * strstr (char * str1, char * str2); example: # include <stdio. h> # include <string. h> int main (void) {char * str1 = "Borland International", * str2 = "nation", * PTR; PTR = strstr (str1, str2 ); printf ("the substring is: % Sn", PTR); Return 0;} function name: strtodd function: convert a string to a double value using the following method: double strtodd (char * STR, char ** endptr); example: # include <stdio. h> # include <stdlib. h> int main (void) {char I Nput [80], * endptr; double value; printf ("enter a floating point number:"); gets (input); value = strtodd (input, & endptr ); printf ("the string is % s the number is % LFN", input, value); Return 0;} function name: strtok function: method for Finding words separated by the delimiters specified in the second string: char * strtok (char * str1, char * str2); example: # include <string. h> # include <stdio. h> int main (void) {char input [16] = "ABC, D"; char * P;/* strtok places a null termin Ator in front of the token, if found */P = strtok (input, ","); If (p) printf ("% Sn", P ); /* a second call to strtok using a null as the first parameter returns a pointer to the character following the token */P = strtok (null, ","); If (P) printf ("% Sn", P); Return 0;} function name: strtol function: convert a string to a long integer using the long strtol (char * STR, char ** endptr, int base); example: # include <stdlib. h> # include <stdio. h> int Mai N (void) {char * string = "87654321", * endptr; long lnumber;/* strtol converts string to long integer */lnumber = strtol (string, & endptr, 10); printf ("string = % s long = % ldn", String, lnumber); Return 0;} function name: strupr function: converts lowercase letters in a string to uppercase letters. Usage: char * strupr (char * Str); example: # include <stdio. h> # include <string. h> int main (void) {char * string = "abcdefghijklmnopqrstuvwxyz", * PTR;/* converts string To upper case characters */PTR = strupr (string); printf ("% Sn", PTR); Return 0;} function name: swab function: swap byte method: void swab (char * From, char * To, int nbytes); example: # include <stdlib. h> # include <stdio. h> # include <string. h> char source [15] = "rfna koblrna D"; char target [15]; int main (void) {swab (source, target, strlen (source )); printf ("this is target: % Sn", target); Return 0;} PS: isalpha () is a character function, not a string Function, Isalpha prototype: extern int isalpha (int c); usage: # include <ctype. h> function: determines whether the character C is an English letter Description: When C is an English letter A-Z or A-Z, return a non-zero value, otherwise return zero. Example: // isalpha. C # include <syslib. h> # include <ctype. h> # include <stdio. h> main () {int C; clrscr (); // clear screen printf ("press a key"); For (;) {c = getchar (); clrscr (); printf ("% C: % s letter", C, isalpha (c )? "Is": "not");} return 0; // just to avoid warnings by compiler} 19 | comment