Question

C PROGRAM

When you print out the old and new bitsets, which are of type unsigned char, please use the %p control character in the printff statement rather than %x or %d or %c. The compiler will complain, but we don't always listen to them anyway. The difference is it will print the bitset out in hex with a preceeding %0x.

unsigned char bitset = 0x14 ;

printf("Bitsrt is %p\n", bitset) ; results in Bitset is 0x14, which is what we want.

How to obtain input from the user and assign it to an unsigned char ?

One way to do this as follows:

               unsigned int Hoboo ; unsigned char bitset ;

             printf("Please enter your bitset using either 0x$$ or $$ where $ is a digit in base 16 (0 - F) -->") ;

              scanf("%x", &Hoboo) ; // interprets input as hex format

               bitset = (unsigned char) Hoboo ;

Whatever the user enters will be interpreted as a hex number. So entering 21 is 21 hex or 33 decimal. Similarly, the user could enter 0x21 which is also 33 decimal.

HW4 Write four functions in C: • ISSET (unsigned char BitSet, int BitPos) returns a 0 if the bit in the given Bit position is a 0 and a 1 if it is 1. • ADDBIT (unsigned char *BitSet, int BitPos) sets the bit in the requested bit position leaving all other bits unchanged. • DELBIT(unsigned char *BitSet, int BitPos) deletes (i.e., sets to 0) the bit in the requested bit position leaving the others unchanged.

Answer 1

Find the code for the above question below, read the comments provides in the code for better understanding. If found helpful please do upvote this.

Note : In the code below bit 1 is the LSB

Code

//stdio is standard library for basic I/O opearertion

#include <stdio.h>

#include<stdlib.h>

#include<string.h>//for string opertions

//this method checks if the given bit ata a particular position is 0 or 1

//note that bit 1 is the LSB

int isset(unsigned char bitset, int pos){

    int val=bitset;//convert the bitset to int

    //now if 2^pos-1 & val == 1 then bit is set else not

    if (val & (1 << (pos - 1)))

        return 1;

    else

        return 0;

}

//sets the bit at a given postion to 1

//note that bit 1 is LSB

void addbit(unsigned char *bitset, int pos){

   int val=*bitset;//get teh decimal number of the bitset

   val |= 1 << pos-1;   //or with 2^pos-1 sets the bit at the given positon

   *bitset=(unsigned char)val;//changes the bitset to the modified value

}

//unsets the bit at a given postion to 1

//note that bit 1 is LSB

void delbit(unsigned char *bitset, int pos){

   int val=*bitset;//get teh decimal number of the bitset

   val &= ~(1 << pos-1);    //and with the negation with 2^pos-1 unsets the bit at the position

   *bitset=((unsigned char)val);//changes the bitset to the modified value

}

//print all teh bits in teh bitset

void printBits(unsigned char bitset){

    char output[8];//stores the bits in a character array

    itoa(bitset, output, 2);//convert the value to binary

    strrev(output);//reverse the array so that 0th index is the LSB

    printf("1st Bit is the LSB");

    //iterate and print all the bits

    for(int i=0;i<strlen(output);i++){

        printf("\nThe bit in position %d id %c",i+1,output[i]);

    }

}

//maind river code of the program

int main()

{

    //to get user input

    unsigned int Hoboo;

    unsigned char bitset;//bitset for the user input

      printf("Please enter your bitset using either 0x$$ or $$ where $ is a digit in base 16 (0 - F) -->");

      scanf("%x", &Hoboo); // interprets input as hex format

    

      bitset = (unsigned char)Hoboo;

//run a loop until user exits it

    while(1){

        int ch;

        //show choices to the user

        printf("\nPlease choose your option 0 - ISSET , 1 = ADD , 2 = DEL , 3 = PRINT , -1 = QUIT : ");

        scanf("%d",&ch);

        if(ch!=-1){

            

        

            if(ch==0){

                int pos;

                printf("\nEnter the bit position to check(1 is th LSB) :");

                scanf("%d",&pos);

                int val=isset(bitset,pos);//call the isset method to check if bit is set or not

                if(val==0)  //val=0 menas bit is set else not set

                    printf("Bit in position %d was not set\n",pos);

                else

                    printf("Bit in position %d was set\n",pos);

            }

            //this is for settign bit at the given pos to 1

            else if(ch==1){

                int pos;

                printf("\nEnter the bit position to set(1 is th LSB) :");

                scanf("%d",&pos);

                printf("\nOld Bitset %p ",bitset);

                addbit(&bitset, pos);

                printf(" , New Bitset %p",bitset);

            }

            //this is for settign bit at the given pos to 0

            else if(ch==2){

                int pos;

                printf("\nEnter the bit position to unset(1 is th LSB) :");

                scanf("%d",&pos);

                printf("\nOld Bitset %p ",bitset);

                delbit(&bitset, pos);

                printf(" , New Bitset %p",bitset);

            }

            //this if for printing teh bits

            else if(ch==3){

                printBits(bitset);

            }

        }

        else{

            exit(0);

        }

        

    }

   

    printf("%p\n\n",bitset);

    printBits(bitset);

    int chk=isset(bitset , 1);

    printf("\n%d",chk);

}

//stdio is standard library for basic I/O opearertion #include <stdio.h> #include<stdlib.h> #include<string.h>//for string opertions, //this method checks if the given bit ata a particular position is 0 or 1 //note that bit 1 is the LSB int isset(unsigned char bitset, int pos) { int val=bitset;//convert the bitset to int //now if 2^pos-1 & val == 1 then bit is set else not if (val & (1 «< (pos - 1))) return 1; else return 0; 13 15 17 //sets the bit at a given postion to 1 //note that bit 1 is LSB void addbit(unsigned char *bitset, int pos) { int val=*bitset;//get teh decimal number of the bitset, val 1= 1 << pos-1; //or with 2^pos-1 sets the bit at the given positon *bitset=(unsigned char) val;//changes the bitset to the modified value 20 29 //unsets the bit at a given postion to 1 //note that bit 1 is LSB void delbit(unsigned char *bitset, int pos) { int val=*bitset;//get teh decimal number of the bitset, val &= ~(1 « pos-1); //and with the negation with 2^pos-1 unsets the bit at the position *bitset=((unsigned char)val);//changes the bitset to the modified value } //print all teh bits in teh bitset void printBits(unsigned char bitset) { char output[8];//stores the bits in a character array, itoa(bitset, output, 2);//convert the value to binary, strrev(output);//reverse the array so that oth index is the LSB printf("1st Bit is the LSB"); //iterate and print all the bits for(int i=0;i<strlen(output);i++){ printf("\nThe bit in position %d id %c",i+1, output[i]);

//maind river code of the program int main() //to get user input unsigned int Hoboo; unsigned char bitset;//bitset for the user input printf("Please enter your bitset using either ox$$ or $$ where $ is a digit in base 16 (0 - F) -->"); scanf("%x", &Hoboo); // interprets input as hex format bitset = (unsigned char)Hoboo; //run a loop until user exits it while(1){ int ch; // show choices to the user printf("\nPlease choose your option 0 - ISSET , 1 = ADD , 2 = DEL , 3 = PRINT, -1 = QUIT : "); scanf("%d",&ch); if(ch!=-1){ if(ch==0) { int pos; printf("\nEnter the bit position to check(1 is th LSB) :"); scanf("%d",&pos); int val=isset(bitset,pos);//call the isset method to check if bit is set or not if(val==0) //val=0 menas bit is set else not set printf("Bit in position %d was not set\n", pos); else printf("Bit in position %d was set\n", pos); //this is for settign bit at the given pos to 1 else if(ch==1) { int pos; printf("\nEnter the bit position to set(1 is th LSB) :"); scanf("%d",&pos);

PIINILI SHILIILEI LIIC DIL PUSILIUL CU SCL115 LILLJD) . , scanf("%d",&pos); printf("\nold Bitset %p ", bitset); addbit(&bitset, pos); printf(" , New Bitset %p", bitset); //this is for settign bit at the given pos to o else if(ch==2) { int pos; printf("\nEnter the bit position to unset(1 is th LSB) :"); scanf("%d",&pos); printf("\nold Bitset %p ", bitset); delbit(&bitset, pos); printf(" , New Bitset %p", bitset); //this if for printing teh bits else if(ch==3){ printBits(bitset); else{ exit(0); 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 printf("%p\n\n", bitset); printBits (bitset); int chk=isset(bitset , 1); printf("\n%d", chk); }

Output

Please enter your bitset using either ox$$ or $$ where $ is a digit in base 16 (0 - F) -->21, Please choose your option 0 - ISSET , 1 = ADD , 2 = DEL , 3 = PRINT , -1 = QUIT : 3, 1st Bit is the LSB The bit in position 1 id 1 The bit in position 2 id o The bit in position 3 id o The bit in position 4 id o The bit in position 5 id o The bit in position 6 id 1 Please choose your option 0 - ISSET , 1 = ADD , 2 = DEL , 3 = PRINT, -1 = QUIT : 1 Enter the bit position to set(1 is th LSB) :3 old Bitset 0000000000000021_, New Bitset 0000000000000025 Please choose your option 0 - ISSET, 1 = ADD , 2 = DEL , 3 = PRINT , -1 = QUIT : 3 1st Bit is the LSB The bit in position 1 id 1 The bit in position 2 id o The bit in position 3 id 1 The bit in position 4 id o The bit in position 5 id o The bit in position 6 id 1 Please choose your option 0 - ISSET , 1 = ADD , 2 = DEL , 3 = PRINT, -1 = QUIT : 0 Enter the bit position to check(1 is th LSB) :4, Bit in position 4 was not set Please choose your option 0 - ISSET , 1 = ADD , 2 = DEL , 3 = PRINT , -1 = QUIT : -1 Ds Colchong

Check the output carefully , it is same as expected