Loop not working Correctly

Hi,
I am working on image steganography code using MATLAB and s, n, p are calculated values which I am getting as per requirement but struggling to get “Bits_to_Modify ” column result shown in below table

Output of Existing program

Code:

---

My text=’ab’
    TextLength=2
    Binary representation of text:
    s= 0110000101100010 
    n=8 (Textlength*4)
    p=
    2
    0
    1
    2
    0
    1
    2
    0

---

First converting text to bytes, then calculating index variable (called as p) & formula is MOD(No of Bytes,3).I have text length as 2 bytes so Index Variable (P) is 2..

I will always have index variable values as 0 or 1 or 2 which will be based on no. of Bytes I have assigned

Quote:

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for first two bits (01) , index variable assigned as 2
for next two bits (10), index variable assigned as 0
for next two bits (00), index variable assigned as 1
for next two bits (01), index variable assigned as 2..

---

so on till end of my bits.

In 5th Pixel need to embed the data bits 01 in 6th and 8th bit locations, and next value of p becomes 0. Need to embed the next data bits 10 into 6th Pixel in 6th and 7th bit locations, next value of p becomes 1. Now need to embed the next two bits 00 into 7th Pixel in 7th and 8th bit locations and so on.

Code:

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Pixcel      IndexVariable        Bits_to_Modify
5          2                      b6=0 b8=1
6          0                      b6=1 b7=0
7          1                      b7=0 b8=0
8          2                      b6=0 b8=1
9          0                      b6=0 b7=1
10          1                      b7=1 b8=0
11          2                      b6=0 b8=0
12          0                      b6=1 b7=0

---

Question

I have written the following program syntax most same to C, taking above values of S,n & P which i am getting

but it dont give following output..It keeps repeating values in output..I have tried logic on paper and looks correct. Please provide me direction for what i am missing in logic

Code:

---

for j=0:2:2*n-2
  for i=1:1:n
    if p(i)==2
    p1= p(i)
    pv=(i+4)
    b6=s(j+1)
    b8=s(j+2)
    end    if p(i)==0
    p1= p(i)
    pv=(i+4)
    b6=s(j+1)
    b7=s(j+2)
    end    if p(i)==1
    p1= p(i)
    pv=(i+4)
    b7=s(j+1)
    b8=s(j+2)
    end   
end
end

---

Expected Output

Code:

---

p1=2
pv=5
b6=0
b8=1
p1=0
pv=6
b6=1
b7=0
p1=1
pv=7
b7=0
b8=0
p1=2
pv=8
b6=0
b8=1
p1=0
pv=9
b6=0
b7=1
p1=1
pv=10
b7=1
b8=0
p1=2
pv=11
b6=0
b8=0
p1=0
pv=12
b6=1
b7=0

---

There is nothing "same to C" here I'm afraid. Please post in the appropriate forum.

Quote:

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Originally Posted by claudiu

There is nothing "same to C" here I'm afraid. Please post in the appropriate forum.

---

Hi,

Equivalent c code could be

s string/numeric array with following values
p string/numeric array with following alues

Code:

---

s= 0110000101100010 
    n=8
    p=
    2
    0
    1
    2
    0
    1
    2
    0

for (j=0;j<2*n-2;j=j+2)
  for (i=1;i<n;i++)
    if p(i)==2
    p1= p(i)
    pv=(i+4)
    b6=s(j+1)
    b8=s(j+2)
    end    if p(i)==0
    p1= p(i)
    pv=(i+4)
    b6=s(j+1)
    b7=s(j+2)
    end    if p(i)==1
    p1= p(i)
    pv=(i+4)
    b7=s(j+1)
    b8=s(j+2)
    end   
end
end

---

For, While and Do While Loops in C - Cprogramming.com
Arrays in C - Cprogramming.com

If you want C, learn C. If you want MATLAB, go find a MATLAB forum.


Quzah.

Quote:

---

Originally Posted by patneel

Hi,

Equivalent c code could be

s string/numeric array with following values
p string/numeric array with following alues

Code:

---

s= 0110000101100010 
    n=8
    p=
    2
    0
    1
    2
    0
    1
    2
    0

for (j=0;j<2*n-2;j=j+2)
  for (i=1;i<n;i++)
    if p(i)==2
    p1= p(i)
    pv=(i+4)
    b6=s(j+1)
    b8=s(j+2)
    end    if p(i)==0
    p1= p(i)
    pv=(i+4)
    b6=s(j+1)
    b7=s(j+2)
    end    if p(i)==1
    p1= p(i)
    pv=(i+4)
    b7=s(j+1)
    b8=s(j+2)
    end   
end
end

---

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Not only are you stubborn but now you have embarked on a crusade to show us we are wrong about what is and is not C. Well then, I think you should be having no problems solving your problem.