String in c programming

String in c programming

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  String in c programming PreparedBy Devan Thakur BCA 1st 29-10-2017 1
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  Strings • A stringis nothing but the collection of the individual array elements or characters. • String is enclosed within Double quotes. • “programming" is a example of String. • Each Character Occupy 1 byte of Memory. • Size of “programming“ = 11 bytes • String is always Terminated with NULL Character (‘0′). char word[20] = “‘p’ , ‘r’ , ‘o’ , ‘g’ , ‘r’ , ‘a’ , ‘m’ , ‘m’ , ‘I’ , ‘n’ , ‘g’ , ‘0’” 29-10-2017 2
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  NULL Character • NULLCharacter is also known as string terminating character. • It is represented by “0”. • NULL Character is having ASCII value 0 • NULL terminates a string, but isn’t part of it • important for strlen() – length doesn’t include the NULL 29-10-2017 3
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  Declaration of astring • Since we cannot declare string using String Data Type, instead of which we use array of type “char” to create String. • Syntax : • char String_Variable_name [ SIZE ] ; • Examples : • char city[30]; • char name[20]; • char message[50]; 29-10-2017 4
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  Rules for declaringa string • String / Character Array Variable name should be legal C Identifier. • String Variable must have Size specified. • char city[]; • Above Statement will cause compile time error. • Do not use String as data type because String data type is included in later languages such as C++ / Java. C does not support String data type • When you are using string for other purpose than accepting and printing data then you must include following header file in your code – #include<string.h> 29-10-2017 5
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  Initializing String (CharacterArray) • Process of Assigning some legal default data to String is Called Initialization of String. • There are different ways of initializing String in C Programming – • Initializing Unsized Array of Character • Initializing String Directly • Initializing String Using Character Pointer 29-10-2017 6
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  Functions of string.h 29-10-20177 Function Purpose Example Output Strcpy(); Makes a copy of a string strcpy(s1, “Hi”); Copies “Hi” to ‘s1’ variable Strcat(); Appends a string to the end of another string strcat(“Work”, “Hard”); Prints “WorkHard” Strcmp(); Compare two strings alphabetically strcmp(“hi”, “bye”); Returns -1. Strlen(); Returns the number of characters in a string strlen(“Hi”); Returns 2. Strrev(); reverses a given string Strrev(“Hello”); olleH Strlwr(); Converts string to lowercase Strlwr(“HELLO”); hello Strupr(); Converts string to uppercase Strupr(“hello”); HELLO
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  String Copy (strcpy) •strcpy( ) function copies contents of one string into another string. • Syntax : strcpy (destination_string , source_string ); • Example: strcpy ( str1, str2) – It copies contents of str2 into str1. strcpy ( str2, str1) – It copies contents of str1 into str2. • If destination string length is less than source string, entire source string value won’t be copied into destination string. • For example, consider destination string length is 20 and source string length is 30. Then, only 20 characters from source string will be copied into destination string and remaining 10 characters won’t be copied and will be truncated. 29-10-2017 8
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  String Concat (strcat) •strncat( ) function in C language concatenates (appends) portion of one string at the end of another string. • Syntax : strncat ( destination_string , source_string, size); • Example : strncat ( str2, str1, 3 ); – First 3 characters of str1 is concatenated at the end of str2. strncat ( str1, str2, 3 ); – First 3 characters of str2 is concatenated at the end of str1. • As you know, each string in C is ended up with null character (‘0’). • In strncat( ) operation, null character of destination string is overwritten by source string’s first character and null character is added at the end of new destination string which is created after strncat( ) operation.29-10-2017 9
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  String Compare (strcmp) •strcmp( ) function in C compares two given strings and returns zero if they are same.  If length of string1 < string2, it returns < 0 value that is -1.  If length of string1 > string2, it returns > 0 value that is 1  If length of string1 = string2 it returns 0. • Syntax : strcmp (str1 , str2 ); • strcmp( ) function is case sensitive. i.e, “A” and “a” are treated as different characters. 29-10-2017 10
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  String Length (strlen) •strlen( ) function in C gives the length of the given string. • Syntax : strlen(str); • strlen( ) function counts the number of characters in a given string and returns the integer value. • It stops counting the character when null character is found. Because, null character indicates the end of the string in C. 29-10-2017 11
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  FAQ’S • How todeclare character array? • Define string? • What are various functions of string? • How to compare to strings? 29-10-2017 12
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  Bibliography • https://www.programiz.com/c-programming/c-string-examples • https://www.tutorialspoint.com/cprogramming/c_strings.htm •http://www.cprogramming.com/tutorial/c/lesson9.html • http://fresh2refresh.com/c-programming/c-strings/ 29-10-2017 13
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  THANK YOU 29-10-2017 14