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printf changes array

Oct 25, 2016 at 5:11pm
Xnot (6)
Hei together
I want to read a data with binarys in. then i want to print them out in Octets(bytes but here I have to name them octets). Now I startet, and everything went great, but only for the first octet, that's right.
the second Octet is wrong. But I only realized is when I printed the whole data in one string to compare. when i print the whole string, the the octets change! So i think both Problems are part of a bigger problem, I cant localize.

Here my code:
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void buildOctets(int n, int m, char* c, char* buffer){
	int i = 0;
	for(int j= 0;j<n;j++){

		for(int k = 0;k<m;k++){

			c[k+j*m]=buffer[i];

			i++;
		}
	}
}
void PrintOctet(char* octet){

	for(int i = 0; i<8;i++){
		printf("%c",octet[i]);
	}
}
void PrintOctets16(char* c){

    for (int i = 0; i<128;i++){

    	PrintOctet(&c[i]);
    	printf("\t");
    	if(i%2==1){
    		printf("\n");
    	}
    }
}

int main() {

ifstream file("/home/florian/workspace/Dec1/Debug/data.dat", std::ios::binary);

    if (!file)
    {
        cout << "file not open\n";
        return 1;
    }

	char *buffer = new char[8*128];
    if (!file.read(buffer, 8*128))
    {
        cout << "file read error\n";
        return 2;
    }

   // char * cPointer;

    //cPointer = new char[128*8];
    char c[128][8];
    char* cPointer = &c[0][0];

    //füllt buffer in c rein
    buildOctets(128,8,cPointer,buffer);

    //printf("%s",&cPointer[0]);

    int size = file.tellg();

    PrintOctets16(cPointer);
	return 0;
}


ok with the printf function is it like this:


011010111000101101000101011001110011001001111011001000111100011...
10101110	01011100	
10111000	01110001	
11100010	11000101	
10001011	00010110	
00101101	01011010	
10110100	01101000	
11010001	10100010


and with no printf is it like:


01101011	11010111	
10101110	01011100	
10111000	01110001	
11100010	11000101	
10001011	00010110	
00101101	01011010	
10110100	01101000	
11010001	10100010	
01000101	10001010


this are only parts of the output.

but the data.dat starts like:

0110101110001011010001010110011100110010011110110010001111
Last edited on Oct 25, 2016 at 5:13pm
Oct 25, 2016 at 5:29pm
cire (8284)
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void PrintOctets16(char* c){

    for (int i = 0; i<128; i++ i += 8){

    	PrintOctet(&c[i]);
    	printf("\t");
    	if(i%2==1){
    		printf("\n");
    	}
    }
}
Oct 25, 2016 at 5:36pm
Xnot (6)
Thank u very much, this problem is solved, but uf is with the
printf("%s",&cPointer[0]);

expression, why does sshe changes the outcome?
Oct 25, 2016 at 5:49pm
cire (8284)
%s tells printf that you are supplying it with a C-style nul-terminated string. You are not supplying it with one of those, so don't tell it you are.
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