CS201-17 - Introduction to Programming Introduction to...

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Unformatted text preview: Introduction to Programming Introduction to Programming Lecture 17 String Handling String Handling String Manipulation Functions String Manipulation Functions Character ASCII ASCII 1 byte = 8 bits 1 byte = 8 bits Example 1 Example 1 #include<iostream.h> main ( ) { int i ; char c ; for( i = 0; i < 256 ; i ++ ) { c = i ; cout << i << “\t” << c <<endl ; } } Header File Header File #include<ctype.h> ctype.h ctype Functions ctype Functions int isdigit ( int c ) int isalpha ( int c ) int isalnum ( int c ) int isxdigit ( int c ) int islower ( int c ) int isupper ( int c ) int tolower ( int c ) int toupper ( int c ) int isspace ( int c ) int iscntrl ( int c ) int ispunct ( int c ) int isprint ( int c ) int isgraph ( int c ) isdigit ( ) Function isdigit ( ) Function int isdigit ( int c ) ; isalpha ( ) Function isalpha ( ) Function int isalpha ( int c ) ; isalnum ( ) Function isalnum ( ) Function int isalnum ( int c ) ; islower ( ) Function islower ( ) Function int islower ( int c ) ; isupper ( ) Function isupper ( ) Function int isupper ( int c ) ; tolower ( ) Function tolower ( ) Function int tolower ( int c ) ; toupper ( ) Function toupper ( ) Function int toupper ( int c ) ; getchar ( ) ; getchar ( ) ; cout << “Please enter a character string then press enter”; cout << “Please enter a character string then press enter”; while ( ( c = getchar ( ) ) != ‘\n’ ) { if ( islower ( c ) ) lc ++ ; else if ( isupper ( c ) ) uc ++ ; else if (isdigit ( c ) ) dig ++; else if ( isspace ( c ) ) ws ++ ; else if ( ispunct ( c ) ) pun ++ ; else oth ++ ; } String Conversion Functions String Conversion Functions double atof ( char * str ) int atoi (char * str ) long atol (char * str ) atoi ( ) Function atoi ( ) Function char str [ ] ; int age ; age = atoi ( str ) ; atof ( ) Function atof ( ) Function 12.89 atof ( ) Function atof ( ) Function char str [ ] ; double dVar ; dVar = atof ( str ) ; int main (int agrc, char **agrv ) ‘argc’ stands for a count of the number of arguments ‘argv’ stands for a vector of arguments String Functions String Functions String Manipulation Functions Function prototype Function description char *strcpy( char *s1, Copies string s2 into array s1. The value of s1 is const char *s2 ) returned. char *strncpy( char *s1, Copies at most n characters of strings2 into array s1. const char *s2, size_t n) The value of s1 is returned. int strcmp( const char *s1, Compares strings1 to s2 const char *s2 ); Returns a negative number ifs1 < s2, zero if s1 == s2 or a positive number ifs1 > s2 int strncmp( const char *s1, Compares up to n characters of strings1 to s2 const char *s2, size_t n ); Returns values as above Appends string s2 to array s1. The first character of s2 overwrites the terminating null character of s1. The value of s1 is returned. char *strncat( char *s1, Appends at most n characters of strings2 to array s1. const char *s2, size_t n ) The first character ofs2 overwrites the terminating null character ofs1. The value of s1 is returned. char *strcat( char *s1, const char *s2 ) int sum ; int sum ; int sum_even ; int sum_odd ; myStrcpy ( ) ; String Manipulation Functions String Manipulation Functions char * strcpy (char *s1 , const char *s2 ) ; char * strncpy ( char *s1 , char *s2 , int n ) ; char * strcat (char *s1 , char *s2 ) ; char * strncat ( char *s1 , char *s2 , int n ) ; strcmp ( ) Function strcmp ( ) Function int strcmp (const char *s1 , const char *s2 ) ; strncmp ( ) Function strncmp ( ) Function int strncmp ( const char *s1 , const char *s2 , int n ) ; strlen ( ) Function strlen ( ) Function int strlen ( const char *s ) ; Search Functions Search Functions Function prototype char *strchr( const char *s, int c ); size_t strcspn( const char *s1, const char *s2 ); size_t strspn( const char *s1, const char *s2 ); char *strpbrk( const char *s1, const char *s2 ); Function description Locates the first occurrence of characterc in string s. If c is found, a pointer to c in s is returned. Otherwise, a NULL pointer is returned. Determines and returns the length of the initial segment of string 1 consisting of s characters not contained in string s2. Determines and returns the length of the initial segment of strin s1 consisting only g of characters contained in strings2. Locates the first occurrence in strings1 of any character in strings2. If a character from string s2 is found, a pointer to the character in stri g s1 is returned. Othern wise, a NULL pointer is returned. char *strrchr( const char *s, Locates the last occurrence ofc in string s. If c is found, a pointer to c in string s is int c ); returned. Otherwise, a NULL pointer is returned. char *strstr( const char *s1, Locates the first occurrence in strings1 of string s2 . If the string is found, a pointer const char *s2 ); to the string in s1 is returned. Otherwise, a NULL pointer is returned. char *strtok( char *s1, const A sequence of calls to strtok breaks string s1 into “tokens”—logical pieces such char *s2 ); as words in a line of text—separated by characters contained in strings2. The first call contains s1 as the first argument, and subsequent calls to continue tokenizing the same string contain NULL as the first argument. A pointer to the current token is returned by each call. If there are no more tokens when the function is called, ULL N is returned. This is a test This is a test “ “ wrong ‘ ‘ right NULL ...
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This note was uploaded on 01/12/2010 for the course CS CS 201 taught by Professor Dr.naveedmalik during the Spring '09 term at Virtual University of Pakistan.

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