Operation on string presentation
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This document provides an overview of string operations in C including: - How strings are stored in memory with a null terminator - Input and output of strings using scanf and printf - Common string library functions like strcpy, strcat, and strlen - Examples of justifying and manipulating strings
![Strings
• C implements the stringstring data structure using
arrays of type char.
• You have already used the string extensively.
– printf(“This program is terminated!n”);
• Since stringstring is an array, the declaration of a
string is the same as declaring a char array.
– char string_var[30];
– char string_var[20] = “Initial value”;](https://image.slidesharecdn.com/operationonstringpresentation-170418210150/85/Operation-on-string-presentation-3-320.jpg)
![Memory Storage for a String
• The string is always ended with a nullnull
charactercharacter ‘0’‘0’.
• The characters after the null character are
ignored.
• e.g., char str[20] = “Initial value”;
n i t i a l v a l u e ? ? …I 00
[0] [13]](https://image.slidesharecdn.com/operationonstringpresentation-170418210150/85/Operation-on-string-presentation-4-320.jpg)
![Memory Storage for a String
• An array of strings is a two-dimensional array of
characters in which each row is one string.
– char names[People][Length];
– char month[5][10] = {“January”,
“February”, “March”, “April”,
“May”};](https://image.slidesharecdn.com/operationonstringpresentation-170418210150/85/Operation-on-string-presentation-5-320.jpg)
![Functions strcat and strlen
• Functions strcat and strncat concatenate
the fist string argument with the second string
argument.
– strcat(dest, “more..”);
– strncat(dest, “more..”, 3);
• Function strlen is often used to check the
length of a string (i.e., the number of characters
before the fist null character).
– e.g., dest[6] = “Hello”;
strncat(dest, “more”, 5-strlen(dest));
dest[5] = ‘0’;](https://image.slidesharecdn.com/operationonstringpresentation-170418210150/85/Operation-on-string-presentation-11-320.jpg)
Operation on string presentation
- 1. Submited by: Md: Aliul Kadir akib Daffodil international university mail:aliulkadir@gmail.com Welcome to CSE PRESENTATION Topics: Operation On String
- 2. 1.Strings 2.Memory Storage for a String 3.Input/Output of a String Right and Left Justification of Strings An Example of Manipulating String with scanf and printf String Library Functions Some String Functions from String.h Functions strcat and strlen Character Analysis and Conversion CONTENT
- 3. Strings • C implements the stringstring data structure using arrays of type char. • You have already used the string extensively. – printf(“This program is terminated!n”); • Since stringstring is an array, the declaration of a string is the same as declaring a char array. – char string_var[30]; – char string_var[20] = “Initial value”;
- 4. Memory Storage for a String • The string is always ended with a nullnull charactercharacter ‘0’‘0’. • The characters after the null character are ignored. • e.g., char str[20] = “Initial value”; n i t i a l v a l u e ? ? …I 00 [0] [13]
- 5. Memory Storage for a String • An array of strings is a two-dimensional array of characters in which each row is one string. – char names[People][Length]; – char month[5][10] = {“January”, “February”, “March”, “April”, “May”};
- 6. Input/Output of a String • The placeholder %s%s is used to represent string arguments in printf and scanf. – printf(“Topic: %sn”, string_var); • The string can be right-justified by placing a positive number in the placeholder. – printf(“%8s%8s”, str); • The string can be left-justified by placing a negative number in the placeholder. – Printf(“%-8s%-8s”, str);
- 7. Right and Left Justification of Strings The “%8s%8s” placeholder displays a string which is right- justified and in 8-columns width. If the actual string is longer than the width, the displayed field is expanded with no padding.
- 8. Copyright ©2004 Pearson Addison-Wesley. All rights reserved. An Example of Manipulating String with scanf and printf The dept is the initial memory address of the string argument. Thus we don’t apply the & operator on it.
- 9. String Library Functions • The string can not be copied by the assignment operator ‘=’. – e..g, “str = “Test String”” is not valid. • C provides string manipulating functions in the “string.h” library. – The complete list of these functions can be found in Appendix B of the textbook.
- 10. Some String Functions from String.h Function Purpose Example strcpy Makes a copy of a string strcpy(s1, “Hi”); strcat Appends a string to the end of another string strcat(s1, “more”); strcmp Compare two strings alphabetically strcmp(s1, “Hu”); strlen Returns the number of characters in a string strlen(“Hi”) returns 2. strtok Breaks a string into tokens by delimiters. strtok(“Hi, Chao”, “ ,”);
- 11. Functions strcat and strlen • Functions strcat and strncat concatenate the fist string argument with the second string argument. – strcat(dest, “more..”); – strncat(dest, “more..”, 3); • Function strlen is often used to check the length of a string (i.e., the number of characters before the fist null character). – e.g., dest[6] = “Hello”; strncat(dest, “more”, 5-strlen(dest)); dest[5] = ‘0’;
- 12. Character Analysis and Conversion • The <ctype.h><ctype.h> library defines facilities for character analysis and conversion. Functions Description isalpha Check if the argument is a letter isdigit Check if the argument is one of the ten digits isspace Check if argument is a space, newline or tab. tolower Converts the lowercase letters in the argument to upper case letters.