- A string is an array of characters in C
- Any group of Chars in “” is a string const
- \” for including double quotes in const
- Common Operations performed are
- Reading and writing
- Combining, copying and comparing
- Extracting portion of it
Declaring and Initializing
- char string_name[size]
- Here size should be no of characters + 1
- While supplying a string to a char array, compiler auto adds null char at the end
- char city[5]= “Surat”
- char city [5]={‘S’,’u’,’r’,’a’,’t’,’\0’}
- Size can be omitted while initializing
Writing Strings
- %s and %w.d s
- When w is zero, nothing gets printed
- The runtime provision for w and d with printf( “%*.*s”, w,d, string) specification
- It’s handy in printing sequence of characters for a given string in style
- Minus sign for left justification
Arithmetic Operation on Chars
- char ch=‘a’; printf (“%d”,ch) will print 97
- x = ‘z’ – 1 assigns 121 to x
- ch >=‘A’ && ch <=‘Z’
- x= character – ‘0’ converts a character digit to it’s equivalent digit
- atoi is a function which converts a string of digits to a number
Putting String Together
- string1 = string 2 is invalid!
- string 3 = string1 + string2 is invalid!
- Need to write special routines to concatenate two or more strings
- if (name1 == name2) or (name1 = “Jay”) are invalid expressions for string
- C has a rich set of string manipulation functions
Few String Handling Functions
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Function
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Action
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strcat()
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Cancatenate two strings
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strcmp()
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Compare two strings
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strcpy()
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Copies one string over another
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strlen()
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Finds the length of a string
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strcat(str1,str2) Statement
- part1 = very \0 part2 = good\0
- part3 = bad\0
- After Execution of strcat(part1,part2)
- part1= very good\0 part2 = good\0
- str1 must be large enough!
- Nested strcat like strcat(strcat(str1,str2),str3 ) is allowed, result is stored in str1
strcmp() Function
- It compares two strings identified by the arguments and returns 0 if they are equal
- If they are not, it has the numerical difference between the first non matching characters in the string
- strcmp(“their”,”there”) will return –9 because it’s the difference between ASCII value of i and ASCII value of r
strcpy() Function
- It acts as a string assignment operator
- It takes the form strcpy(string1,string2)
- It assigns the contents of string2 to string1
- string2 can be a string constant like strcpy(string1,”Delhi”)
- strcpy(city1,city2) will assign contents of city2 to city1
strlen() Function
- This function counts and returns no of characters in a string
- n = strlen(string1)
- Here n is an integer variable which receives the value of length of string
- The argument may be a string constant
- The counting ends at the first null character
Table of Strings
- List of names of employees of a company, list of names of students etc are needed
- student[30][15] can be used to store 30 student names of max 15 chars
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C
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h
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a
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n
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d
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i
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g
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a
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r
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h
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M
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a
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d
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r
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a
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s
| | | | |
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M
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u
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m
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b
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a
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i
| | | | |
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A
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h
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m
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e
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d
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a
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b
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a
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d
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H
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y
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d
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r
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a
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b
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a
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d
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Easier Way to Store Names
static char city[][]
{“Chandigarh”,
“Madras”
“Ahemdabad”,
“Hydrabad”
“Mumbai”
};