PROGRAM
/* Program 10
 * Write functions to implement string operations such as compare, 
 * concatenate, string length. Convince the parameter passing techniques.
 */
 
 #include <stdio.h>
 
 
 // Prototypes for the user defined functions
 int str_length(char []); 
 int str_compare(char [], char []);
 void str_concat(char [], char []);
 
 int main()
 {
 	// Declare the variables
 	char str[50];
 	char str1[50], str2[50];
 	char str_des[100], str_src[50];
 	
 	int length, comp_res;
 	
 	// Accept the string from the user to find the length 
 	printf("\nEnter a string :");
 	scanf("%s",str);
 	
 	// Invoke the function to find the length of the string
 	length = str_length(str);
 	
 	// Print the length of the string
 	printf("The length of %s is %d\n",str,length);
 	
 	// Accept two strings to compare
 	printf("\nEnter two strings for string compare :");
 	scanf("%s%s",str1,str2);
 	
 
 	// Invoke string compare function to compare the str1 and str2 strings
 	comp_res=str_compare(str1,str2);
 	
 	if (comp_res < 0)
 	{
 		printf("String \"%s\" is less than string \"%s\"\n",str1,str2);
 	}
 	else if (comp_res == 0)
 	{
 		printf("String \"%s\" is same as string \"%s\"\n",str1,str2);
 	}
 	else
 	{
 		printf("String \"%s\" is greater than string \"%s\"\n", str1,str2);
 	}
 	
 	// Accept two strings for string concatenation
 	printf("\nEnter two strings for string concatenation :");
 	scanf("%s%s",str_des,str_src);
 
 	// Invoke string concatenation function 
 	str_concat(str_des,str_src);
 	
 	// Print the concatenated string
 	printf("The string after concatenation is \"%s\"\n", str_des);
 	
 	return 1;
 }
 
 int str_length(char s[])
 {
 	int i;
 	for(i=0;s[i]!='\0';i++);
 	return i;
 }
 
 
 int str_compare(char s1[], char s2[])
 {
 	int i,j;
 	for(i=0,j=0;(s1[i] != '\0' && s2[j] != '\0');i++,j++)
 	{
 		if (s1[i] != s2[j])
 		{
 			return (s1[i] - s2[j]);
 		}
 	}
 	if (s1[i] == '\0' && s2[j] == '\0')
 	{
 		return 0;
 	}
 	else if(s1[i] == '\0' || s2[i] == '\0')
 	{
 		return (s1[i] - s2[i]);
 	}
 		
 }
 
 
 void str_concat(char s1[], char s2[])
 {
 	int i,j;
 	for(i=0;s1[i] != '\0';i++);
 	
 	for(j=0;s2[j] != '\0';i++,j++)
 	{
 		s1[i] = s2[j];
 	}
 	s1[i] = '\0';
 }
by

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#include <stdio.h>
int main()
{
    char name[50];
    printf("Enter name:");
    scanf("%s", name);
    printf("Hello %s \n" , name );
    return 0;
    
}

About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition if-else is used.

if(conditional-expression) {
   // code
} else {
   // code
}

You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to if-else-if ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {  
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

How to declare a Function

return_type function_name(parameters);

How to call a Function

function_name (parameters)

How to define a Function

return_type function_name(parameters) {  
  //code
}