Chapter 6 Character and string handling



Character handling functions :
FunctionResult
isalnum(int c)
True if alphabetic or a digit.
Example :
char c='a';
x=isalnum(c) //x=1;(true)
isalpha(int c)
True if alphabetic.
Example :
char c='a';
x=isalpha(c) //x=1;(true)
isdigit(int c)
True if c is a decimal digit.
Example :
char c='a';
x=isdigit(c) //x=0;(false)
isgraph(int c)
True if c is any printing character except space.
Example :
char c='a';
x=isgraph(c) //x=1;(true)
islower(int c)
True if c is any lowercase alphabetic letter.
Example :
char c='a';
x=islower(c) //x=1;(true)
isprint(int c)
True if c is printing character (including space).
Example :
char c='a';
x=isprint(c) //x=1;(true)
isspace(int c)
True if a white space character.
Example :
char c=';';
x=isspace(c) //x=0;(false)
isupper(int c)
True if an uppercase alphabetic letter.
Example :
char c='a';
x=isupper(c) //x=0;(false)
isxdigit(int c)
True if valid hexadecimal digit.
Example :
char c='a';
x=isxdigit(c) //x=1;(true)
Character mapping functions :
FunctionResult
tolower(int c)

convert uppercase letter to lowercase letter.
Example :
char c='A';
x=tolower(c) //x='a';
toupper(int c)
convert lowercase letter to uppercase letter.
Example :
char c='b';
x=toupper(c) //x='B';
String handling functions :
A string is an array of characters.

FunctionResult
strlen(str)
Finds the length of str.
Example :
char str[10]={"cdac"};
int len;
len=strlen(str); //len =4;
strupr(str)
Convert lower string to upper string.
Example :
char str[10]={"cdac"};
strupr(str); //str="CDAC"
strlwr(str)
Convert upper string to lower string.
Example :
char str[10]={"COMPuter"};
strlwr(str); //str="computer"
strcmp(str1,str2)
compares two strings and returns -ve no. if str1 is small , +ve. if str1 is big and 0 if both string are same.
Example :
char str1[10]={"AAA"},str2[10]={"ZZZ"};
int diff;
diff=strcmp(str1,str2)//diff=-ve
strcpy(str1,str2)
Copy str2 to str1(str1=str2).
Example :
char str1[10],str2[10]={"AAA"};
strcpy(str1,str2);//str1="AAA"
strcat(str1,str2)
Concatenates two strings.str1=str1+str2 and str2=str2.
Example :
char str1[10]={"Sita"},str2[10]={"Ram"};
strcat(str1,str2);//str1="SitaRam" and str2="Ram".
strrev(str)
Reverse string.
Example :
char str[10]={"computer"};
strrev(str);//str="retupmoc"


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