Tutorial No. 8 - Solution (Strings and User Defined Functions)

Transcription

1 Tutorial No. 8 - Solution (Strings and User Defined Functions) 1. Explain strcat( ), strcpy( ),strncmp( ) and strstr( ) string manipulation function. [6] strcat() Function: The strcat function joins two strings together. It takes the following form: strcat(string1, string2); where string1 and string2 are character arrays. When the function strcat is executed, string2 is appended to string1. It does so by removing the null character at the end of string1 and placing string2 from there. The string at string2 remains unchanged. a = Hello ; b = World ; strcat(a,b); Now, the string a becomes HelloWorld ; strcpy() Function: The strcpy function works almost like a string-assignment operator which copies one string over another. It takes the following form: strcpy(string1, string2); which assigns the contents of string2 to string1. The statement, strcpy(city, Delhi ); will assign the string Delhi to the string variable city. strncmp() Function: It is a variation of the function strcmp. This function has three parameters in the function call as shown below: strncmp(s1,s2,n); This compares the left-most n characters of s1 to s2 and returns a) 0, if they are equal b) Negative number, if s1 sub-string is less than s2 c) Positive number, otherwise strstr() Function: It is a two parameter function that can be used to locate a sub-string in a string. This takes the following form: strstr (s1, s2); strstr (s1, ABC ); The function strstr searches the string s1 to see whether the string s2 is contained in s1. If yes, the function returns the position of the first occurrence of the sub-string. Otherwise, it returns a NULL pointer.

2 2. Explain getchar() and gets() functions with suitable example. [4] getchar() Function: This function is used for taking a single character as input from standard input device. The general form of getchar() is: int getchar(void); It returns the unsigned char that they read. If end-of-file or an error is encountered getchar() functions return EOF. #include <stdio.h> void main () char c; printf("enter character: "); c = getchar(); printf("character entered: "); putchar(c); gets() Function: It is used to scan a line of text from a standard input device. The gets() function will be terminated by a newline character. The newline character won't be included as part of the string. The string may include white space characters. The general form of gets is: char *gets(char *s); The argument must be a data item representing a string. On successful completion, gets() shall return a pointer to string s. #include <stdio.h> char str[50]; printf("enter a string : "); gets(str); printf("you entered: %s", str); 3. Explain putchar() and puts() functions with suitable example [4] putchar() Function: putchar function displays a single character on the screen. The general form of putchar() is: int putchar(int c); #include <stdio.h> void main () char ch; for(ch = 'A' ; ch <= 'Z' ; ch++) putchar(ch);

3 puts() Function: It is used to display a string on a standard output device. The puts() function automatically inserts a newline character at the end of each string it displays, so each subsequent string displayed with puts() is on its own line. puts() returns non-negative on success, or EOF on failure. #include <stdio.h> char str[50]; printf("enter a string : "); gets(str); printf( The input string is: ); puts(str); 4. Write user defined functions for the following: (i) strlen() : to find length of string. [7] int find_length(char str[]) int len = 0; while( str[len]!= \0 ) len++; return(len); (ii) strcat() : to concate two strings char * concatenation(char a[], char b[]) int i, j; for( i=0; a[i]!= \0 ; i++) for(j=0; b[j]!= \0 ; j++) a[i++] = b[j]; a[i] = \0 ; return a;

4 5. Which are various categories of functions in C. [7] Depending on whether arguments are present or not and whether a value is returned or not, a function may belong to one of the following categories: Category 1: Functions with no arguments and no return values. Category 2: Functions with arguments and no return values. Category 3: Functions with arguments and one return values. Category 4: Functions with no arguments but return values. Category 5: Functions that return multiple values. No arguments and No return values When a function has no arguments, it does not receive any data from the calling function. Similarly when it does not return a value, the calling function does not receive any data from the called function. In effect, there is no data transfer between the calling function and the called function. void funct(); funct(); void funct() printf("hi, this is display from function funct()"); Arguments but No return values We could make the calling function to read data from the terminal and pass it on to the called function. In this type of functions there is a one-way data communication from the calling function to the called function. void funct(int, int); int a,b; printf("enter two numbers :"); scanf("%d %d",&a, &b); funct(a,b); funct(int a, int b) int c; c=a+b; printf("\n Result = %d",c);

5 Arguments with one return values We may not always wish to have the result of a function displayed. We may use it in the calling function for further processing. This category of functions receive values from calling function, does some calculations/ manipulations and sends one of the values back to the calling function. int funct(int, int); int a,b,result; printf("enter a value for a :"); scanf("%d",&a); printf("enter a value for b :"); scanf("%d",&b); result=funct(a,b); printf("\n Result = %d",result); int funct(int a1, int b1) int c; c=a1+b1; return(c); No arguments but return a values In this category of functions, no value is passed from the calling function to the called function but a value is send back to the calling function by the called function. int get_number(); int n=get_number(); printf( %d,n); int get_number() int number; scanf( %d,&number); return number; Functions with multiple return values We use this type of functions when we want to send back more information from the called function to the calling function. The mechanism of sending back information through arguments is achieved using address operator (&) and indirection operator (*).

6 void mathoperation (int, int, int *, int *); int x=20, y=10, s, d; mathoperation(x, y, &s, &d) printf( s=%d \n d=%d,s,d); void mathoperation(int a, int b, int *sum, int *diff) *sum = a+b; *diff = a-b; 6. Explain the difference between call by value and call by reference with suitable examples. [7] Sr. No. Call by Value Call by Reference 1. This is the usual method to call a function in which only the value of the variable is passed as an argument 2. Any alternation in the value of the argument passed is local to the function and is not accepted in the calling program 3. Memory location occupied by formal and actual arguments are different 4. Since a new location is created, this method is slow In this method, the address of the variable is passed as an argument Any alternation in the value of the argument passed is accepted in the calling program(since alternation is made indirectly in the memory location using the pointer) Memory location occupied by formal and actual arguments are same Since the existing memory location is used through its address, this method is fast 5. More memory space is used Less memory space is used 6. There is no possibility of wrong data manipulation since the arguments are directly used in an application 7. void funct(int); int n; There is a possibility of wrong data manipulation since the addresses are used in an expression. A good skill of programming is required here void funct(int *); int n;

7 printf("enter a value for n :"); scanf("%d",&n); funct(n); funct(int a) printf("n = %d",a); printf("enter a value for n :"); scanf("%d",&n); funct(&n); funct(int *a) printf("n = %d",*a); 7. What is recursive function? Explain with suitable example. [7] A function that calls itself is known as recursive function and the process of calling function itself is known as recursion in C programming. While using recursion, programmers need to be careful to define an exit condition from the function, otherwise it will go in infinite loop. Recursive functions are very useful to solve many mathematical problems like to calculate factorial of a number, generating Fibonacci series, etc. //Program for finding Factorial of a number using recursion #include<stdio.h> #include<conio.h> int factorial(int); int n,f; printf("enter a number to find factorial\n"); scanf("%d", &n); f = factorial(n); printf("%d! = %d", n, f); int factorial(int n) if (n == 1) return 1; else return(n * factorial(n-1));

8 8. Write a function which receives number as argument and return sum of digit of that number. [5] int sum_of_digits(int n) int sum=0, remainder; while( n > 0 ) remainder = n % 10; sum = sum + remainder; n = n / 10; return sum; 9. Write a program to generate Fibonacci series of n given numbers using function named fibo. i.e Or Write a program to generate Fibonacci series of n given numbers using recursion. [7] //Program for printing Fibonacci Series using Recursion #include<stdio.h> #include<conio.h> int fibo(int); int n, i; printf("enter the number of terms\n"); scanf("%d",&n); printf("first %d terms of Fibonacci series are :-\n",n); for ( i = 1 ; i <= n ; i++ ) printf("%d\n", fibo(i)); int fibo(int n) if ( n == 1 n == 2 ) return 1; else return ( fibo(n-1) + fibo(n-2) );