STRING STANDARD FUNCTIONS IN C:

• strlen() - Determines the length of a string. 

Eg: char name[]="antony";

       int length;

       length=strlen(name);

       printf("%d",length);

Output:

6

• strcpy(s1,s2) - copies the content of s2 to s1.

Eg: char source[]="hai";

       char destination[3];

       strcpy(destination,source);

       printf("source=%s destination=%s",source,destination);

Output:

source=hai destination=hai

• strncpy(s1,s2,n) - copies 1st n characters from s2 to s1.

Eg: char source[]="hai";

       char destination[3];

       strcpy(destination,source,2);

       printf("source=%s destination=%s",source,destination);

Output:

source=hai destination=ha

• strcmp(s1,s2) - compares two strings. Case sensitive. 

     return value                                       result

          zero                        -                       s1 = s2

       negative                    -                       s1 < s2

       positive                     -                       s1 > s2

Eg: char s1[]="hai";

       char s2[]="hai";

       printf("%d\n",strcmp(s1,s2));

       printf("%d\n",strcmp(s1,"hello"));

       printf("%d\n",strcmp("hello",s1));

Output:

0

-1

1

       

• stricmp(s1,s2) - similar to strcmp(), but it is not case sensitive.
• strncmp(s1,s2,n) - similar to strcmp(), but comparison is done only till n characters
• strnicmp(s1,s2,n) - compares n characters and it is not case sensitive.
• strlwr(s) - convert s to lower case.

Eg: char s[]="ABCDE";

       printf("%s",strlwr(s));

Output:

abcde

• strupr(s) - converts s to upper case.
• strdup(s) - duplicates the given string at the allocated memory which is pointed by a pointer variable.

Eg: char text1[]="hai",*text2;

       text2=strdup(text1);

       printf("original=%s duplicate=%s",text1,text2);

Output:

original=hai duplicate=hai

• strchr(string,ch) - returns the pointer to the first occurence of a given character in the string.

Eg: char s[]="have a nice day!";

       char *c;

       c=strchr(s,'a');

       if(c)

           printf("%c is found",c);

       else

           printf("%c is not found",c);

Output:

a is found

• strrchr(string,ch) -  similar to strchr(). strchr() searches for the occurence of characters from the beginning of the string but strrchr() searches for the occurence of characters from the end.
• strstr(string1,string2) - finds string2 in string1 and returns the pointer to the location from where the second string starts in the first string.

Eg: char str1[]="welcome to my blog!!!";

       char str2[]="welcome";

       char *c;

       c=strstr(str1,str2);

       if(c)

           printf("%s is found",str2);

       else

           printf("%s is not found",str2);

Output:

welcome is found

• strcat(str1,str2) - appends str2 at the end of str1 and the resultant string is stored in str1.

Eg: char s1[]="hai", s2[]="hello";

       strcat(s1,s2);

       printf("%s",s1);

Output:

haihello

• strncat(str1,str2,n) - similar to strcat. 1st n characters of str2 are appended to the end of str1.
• strrev(string) - reverses the string.

Eg: char a[]="hai";

       puts(strrev(a));

Output:

iah

• strset(string,symbol) - replaces every character of the string with the symbol.

Eg: char s[]="hai";

       strset(s,"*");

       printf("%s",s);

Output:

***

• strnset(string,symbol,n) - replaces 1st n characters of the string with the symbol.
• strspn(str1,str2) - returns the no. of characters matched upto the 1st mismatch character.

Eg: char str1[]="hawaii", str2[]="hang";

       int length;

       length=strspn(str1,str2);

       printf("two strings are equal upto %d characters",length);

Output:

two strings are equal upto 2 characters

• strpbrk(str1,ch) - searches the 1st occurence of a character in the given string and then it displays the string starting from that character.

Eg: char s[]="hello world!!!";

       char *ptr;

       ptr=strpbrk(s,'o');

       puts(ptr);

Output:

orld!!!