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int replace_bits(int a, int b, int x, int y)
{
int mask = ((1 << (y - x + 1)) - 1) << x;
// Clear a and replace with that of b
return ((a & ~mask) | (b & mask));
}

s => start bit
e => end bit
first => first value
second => second value

Now

bits = e - s + 1;
mask =( (~0) << ((sizeof(int) * 8) - bits) ) >> ((sizeof(int) * 8) - bits - s) ) ;
(first & ~mask) | (second & mask)

// let the integers be m and n, let the bit positions be x, y
  // let m = 24 , n = 15 , x = 2 , y = 4 
   
   int to_to_anded = pow(2, x - 1)  // for x = 1, generates 1, for 2, 2, for 3, 4
   int i;
   for ( i = x; i <= y; i++) {
         int res = n & to_be_anded ; // get the ith bit value of n
         if (res == 0) {
                // set the ith bit of m to 0
                m = m & ! to_be_added; 
         } else { // set to 1
                m = m | to_be_added;  
        }
        to_be_added = to_be_added << 1;

   }

n and m are the given numbers; i and j are the indices with i>j; the bits in n between i and j are replaced by m.

private static void updateBits(int n, int m, int i, int j) {
			
	int max = ~0;
	
	int a = (1 << (j+1)) - 1;
	
	int b = max - a;
	
	int c = (1 << i) - 1;
	
	int mask = b | c;
	
	int first = n & mask;
	
	int second = m << i;
	
	int soln = first | second;
		
	}

void Swap(uInt Val1, uInt Val2, uInt Pst1, uInt Pst2)
{
Val1 = (((Val1 >> Pst2) << Pst2) | ((Val1 << (32 - Pst1)) >> (32 - Pst1)));
Val2 = ((((Val2 << (32 - Pst2)) >> (32 - Pst2)) >> Pst1) << Pst1);
Val1 = (Val1 | Val2);
}

#include <iostream>

int main()
{
    unsigned int N = 1024;
    unsigned int M = 21;

    unsigned int i = 2, j = 6;

    unsigned int temp = ~0;

    unsigned int left = temp >> (32 - i);
    std::cout << "left: " << left << std::endl;
    unsigned int right = temp << (j + 1);
    std::cout << "right: " << right << std::endl;

    unsigned int res = (N & (left | right)) | (M << i);
    std::cout << "result: " << res << std::endl;

}

//based on 16 bit
int v1 = 1010 1010 1010 1010;
int v2 = 1010 1111 1011 1010;
int i = 10, int j = 3; // both inclusive

int mask = ~0; // 1111 1111 1111 1111
mask = (mask >> i) << i; // 1111 1100 0000 0000 ;

int m1 = (~0) >> (16 - j +1); // 11;

int mask2 = mask & m1; // 1111 1100 0000 0011


int m3 = ~mask2; // 11 1111 1100;
int m4 = v2 & m3; // 11 1011 1000

int result = (mask2 & v1) | (m4) ; // 1010 1000 0000 0010 | 11 1011 1000 = 1010 1011 1011 1010

partial= A&(~0<<i) | (A &(1<<j - 1))
Result = partial | (B<<j)

int insert(int m, int n, int i, int j)
{
    int temp = j - i + 1;
    int temp1 = (1 << temp) - 1;
    int mask = ~(temp1 << i);
    n = n & mask;
    n = n | (m << i);
    return n;
}

int main() {

int num1 = 0xE3, num2 = 0xF2, num3 = 0;
int mask = 0;
int i = 2, j= 4;

num3 = num1 ^ num2;
mask = ((1 << j) - 1) << i;
printf("mask = %d\n", mask);
num3 &= mask;
num2 ^= num3;

printf("%d.\n", num2);
return 0;

}

i & j are integers, & n1 & n2 are bit positions ( n1 > n2)

int n = pow(2,(n1-n2)) -1 ;
   int mask = n << n2;
   i = ( j & ~mask) | ( i & mask);

(a >> p2 & ((1 << p1) -1)) << p2

void set(int * a, int b , int start, int end)
{
int t = end;
int len;
int mask;
if (start>end) {end = start; start=t; }
len = end-start-1;
mask = ((1<<len)-1);

*a= ((*a)& ~(mask<< (start+1))) |((b&mask) << (start +1));
}
Input:
int d = 0xffffff;
int e= 0x01;
set(&d,e,0,4);
out will be: 0xfffff3;

//reaplcebits: takes bits between pos1 and pos2 of input a and put it input b between the
//same positions.
unsigned int replacebits(unsigned int a , unsigned int b,unsigned int pos1, unsigned int pos2)

{
int unsigned tmp , mask , bm;
printf("a==%x b===%x pos1==%x pos2===%x",a,b,pos1,pos2);

//swap pos1 and pos2 if pos1 < pos2

if(pos1<pos2){
tmp=pos2;
pos2=pos1;
pos1=tmp;
}

//number of bits in a mask
bm=pos1-pos2-1;

//prepared mask
mask= ((1<<bm) -1) << (pos1-bm);
printf("mask==%x",mask);

return ((a&mask)|(b&~mask));

}

//reaplcebits: takes bits between pos1 and pos2 of input a and put it input b between the
//same positions.
void replacebits(unsigned int a , unsigned int* b,unsigned int pos1, unsigned int pos2)

{
int unsigned tmp , mask , bm;
printf("a==%x b===%x pos1==%x pos2===%x",a,(*b),pos1,pos2);

//swap pos1 and pos2 if pos1 < pos2

if(pos1<pos2){
tmp=pos2;
pos2=pos1;
pos1=tmp;
}

//number of bits in a mask
bm=pos1-pos2-1;

//prepared mask
mask= ((1<<bm) -1) << (pos1-bm);
printf("mask==%x",mask);

*b = ((a&mask)|(*b&~mask));


}

//reaplcebits: takes bits between pos1 and pos2 of input a and put it input b between the
//same positions.
void replacebits(unsigned int a , unsigned int* b,unsigned int pos1, unsigned int pos2)

{
int unsigned tmp , mask , bm;
printf("a==%x b===%x pos1==%x pos2===%x",a,(*b),pos1,pos2);

//swap pos1 and pos2 if pos1 < pos2

if(pos1<pos2){
tmp=pos2;
pos2=pos1;
pos1=tmp;
}

//number of bits in a mask
bm=pos1-pos2-1;

//prepared mask
mask= ((1<<bm) -1) << (pos1-bm);
printf("mask==%x",mask);

*b = ((a&mask)|(*b&~mask));


}

1 #include<stdio.h>
  2 
  3 void printBinary(int a)
  4 
  5 {
  6 
  7     unsigned int mask,bit,size;
  8 
  9     size = sizeof(int)*8;
 10 
 11     mask = 1 << size-1;
 12 
 13     for(int i =0 ;i<size;i++)
 14 
 15     {
 16 
 17         bit = (a & mask) ? 1 : 0;
 18 
 19         mask = mask >>1;
 20 
 21         printf("%d ",bit);
 22 
 23     }
 24 
 25     printf("\n");
 26 
 27 }
 28 
 29 int setBit(int pos1 , int pos2,int num1,int num2)
 30 
 31 {
 32 
 33     int n = (pos2-pos1)+1;
 34 
 35 
 36     return (num2 | (num1 &((1<<n)-1)<<(pos1-1)));
 37 
 38 }
 39 
 40 int main()
 41 
 42 {
 43 
 44     int num1,num2,pos1,pos2;
 45 
 46     printf("Enter the 1st Number :");
 47 
 48     scanf("%d",&num1);
 49 
 50     printBinary(num1);
 51 
 52     printf("Enter the 2nd Number :");
 53 
 54     scanf("%d",&num2);
 55 
 56     printBinary(num2);
 57 
 58     printf("Enter the 1st position ");
 59 
 60     scanf("%d",&pos1);
 61 
 62     printf("Enter the 2nd position :");
 63 
 64     scanf("%d",&pos2);
 65 
 66 printBinary(setBit(pos1,pos2,num1,num2));
 67 
 68 }