1. C Strings Prabhat Kumar Padhy1 1

2. C Strings? S R I C I T Y \0 S R I C I T Y \0
Strings ? – Is not this a set of characters ?
Character arrays are often called as strings.
String is always terminated by ‘\0’ - NULL
main() {
static char name[] = “SRI CITY”;
int i=0;
while (name[i] = ‘\0’)
printf(“%c”,name[i]);
i++; }
ASCII value of ‘\0’ is 0
A string can also be initialized as static char[] = “SRI CITY”;
main() {
static char name[] = “SRI CITY”;
int i=0;
char *ptr;
ptr = name; //ptr = &name[0];
while (ptr = ‘\0’)
printf(“%c”, ptr);
ptr++; }
S R I C I T Y \0
S R I C I T Y \0

3. C Stings? String elements can also be accessed by the use of Pointers
char name[5][100];
C Stings?
String elements can also be accessed by the use of Pointers
printf and scanf possess simple way of handling string I/O
Main() {
char name[25];
scanf(“%s”,name); // format specification for string is %s
printf(“%s”,name); // format specification for string is %s }
String can be one dimensional character array or two dimensional character array
char name[5][100];
each line in the 2D array is an array of char with size = 100
The above declaration can also be done as below
char *name [100];

4. Pointer, Array / Strings?
char name[5][100];
Pointer, Array / Strings?
Pointers and arrays are very closely linked in C. Think of array elements arranged in consecutive memory locations. For Ex:
char a[10],*p;
P = &a[0]; // pointer “p”, points to address of a[0]
P p++
There is a subtle difference between pointer and array, such as we can write
p=a instead p = &a[0]
a[i] can be written as using pointer *(p+i) => &a[i] = (p+i)
However pointers and arrays are different
Pointer is a variable (p=a; p++; ….)
Array is not a variable, rather a Datatype or data structure  Important point to understand
S R I C I T Y \0

5. Array of Pointers to Strings?
char name[5][100];
Array of Pointers to Strings?
A pointer, points to string. Set of such pointers pointing to different strings in an array, then it is array of pointers to string
6001
6009
6014
6018
Array of pointers names[]
void main() {
static char names[] = {
“SRI CITY”,
“IIIT”,
“IIT”,
IIT TPTY”, };
Int I;
for(i=0;i<3;i++)
printf(“%s\n”,names[i]); }
S R I C I T Y \0
I I I T\0
I I T \0
I I T T P T Y \0

6. Basic String Handling Function
Syntax
Purpose
strlen
Size_t strlen(const char *str)
Finds length of a string
strcpy
Char * strcpy(char *string1,const char *string2)
Copy string2 to string1. 
strncpy
char *strncpy(char *string1,const char *string2, size_t n)
Copy first n characters of string2 to stringl
strcasecmp
int strcasecmp(const char *s1, const char *s2)
It can compare the with case
strncat
char *strncat(char *string1, char *string2, size_t n)
N no of charactrs
Strcmp
int strncmp(char *string1, char *string2, size_t n
Strncmp

7. Strlen without using builtin function?
/* C program to find the length of a string without using the
built-in function */
#include <stdio.h>
void main() {
char string[50];
int i, length = 0;
printf("Enter a string \n");
gets(string);
/* keep going through each character of the string till its end */
for (i = 0; string[i] != '\0'; i++)
length++; }
printf("The length of a string is the number of characters in it \n");
printf("So, the length of %s = %d\n", string, length);

8. Examples / Questions? Ex-3 Ex-1 EX - 2 int main () {
short number,sum; int bignumber,bigsum; char letter;   main() {   }
Examples / Questions?
Ex-3
int main () {
static char str[] = “This is IIITs”;
char *s;
s=&str[6]-6;
while(*s)
printf(“%c”,*s++);
return 0; }
Ex-1
int main () {
static char s[] = “This is IIITs”;
printf(“%d”,*(s+strlen(s)));
return 0; }
EX - 2
int main () {
char ch[20];
int i;
for(i=0;i<19;i++)
*(ch+i) = 67;
*(ch+i)=‘\0’;
printf(“%s”,ch);
return 0; }

9. Examples / Questions? Ex-6 Ex-4 EX - 5 void main() {
short number,sum; int bignumber,bigsum; char letter;   main() {   }
Examples / Questions?
Ex-6
Ex-4
void main() {
static char *names[] = {
“SRI CITY”,
“IIIT”,
“IIT”,
IIT TPTY”, };
int i;
printf(“%d%d\n”, sizeof(names),sizeof(names[i])); }
EX - 5

10. Strlen without using builtin function?
/* C program to find the length of a string without using the
built-in function */
#include <stdio.h>
void main() {
char string[50];
int i, length = 0;
printf("Enter a string \n");
gets(string);
/* keep going through each character of the string till its end */
for (i = 0; string[i] != '\0'; i++)
length++; }
printf("The length of a string is the number of characters in it \n");
printf("So, the length of %s = %d\n", string, length);

11. Questions?