merging two array elements into one

Question

After managing to correctly execute xor of chars between "$" and "*" I need to perform "IF statement" to check if the xor indeed equals "64". I need to merge these two chars and somehow compare to the xor. The problem is i variables type. XOR (sumcheck) is in hex, the b (merging of 6 and 4) is in dec. Should i convert XOR to dec value, or convert 64(dec) to 64(hex) value?

DEMO

#include <stdio.h>

int main(void) {

int i;
int xor = 0;
int b;
// $GPGLL,,,,,,V,N*64

char Received[18]= {'$','G','P','G','L','L',',',',',',',',',',',',','V',',','N','*','6','4'};
int loop;

// display array
//for(loop = 0; loop < 18; loop++)
//   printf("%c ", Received[loop]);

for(int i = 1; i<=14; i++)
    xor ^= Received[i];
    printf("%#02x  ", xor);
    printf("%d ", xor);

    b = ((Received[16]-'0') *10) + Received[17]-'0';
    printf("%d ", b);

if(xor == b){
    printf("WORKING!");
}
else{
    printf("not working");
}

return 0;
}

Not the cause of your problem, but this is wrong: printf("%#02x ", xor, "%d ", xor); it should be printf("%#02x %d\n", xor, xor); — Jabberwocky
– Jabberwocky, Commented Sep 26, 2018 at 9:22
Please don't "correct" the code in your question as the answer bewlow doesn't make sense anymore. If you have another question, ask another question. — Jabberwocky
– Jabberwocky, Commented Sep 26, 2018 at 9:44

kiran Biradar · Accepted Answer · 2018-09-26 09:50:58Z

1

You cannot pass a char to atoi because it expects its input to be pointer to char (char*).

If you wants to use atoi you need to form the string yourself and pass it to atoi as below.

 char a[3] = {Received[16],Received[17]};
 b = atoi(a); //Base 10

Use strol for base 16(HEX) as below

 b = strtol(a,NULL,16);

If you don't want to use atoi or strol you can do as below.

 b = ((Received[16]-'0') *10) + (Received[17]-'0'); //Base 10
 b = ((Received[16]-'0') *16) + (Received[17]-'0'); //Base 16

edited Sep 26, 2018 at 9:50

answered Sep 26, 2018 at 9:22

kiran Biradar

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4 Comments

kabanos Over a year ago

atoi did work, however i wasn't able to display it. Second option is easier. Also i still have problems with the variables.. DEMO Am i right? i need to convert hex (xor sumcheck) value to dec?

kiran Biradar Over a year ago

@kabanos I'm not able to access your Link. What problems you are having with variables?

kabanos Over a year ago

i've updated the question, your answer was very helpful. however now i need to perform if statement to check if xor (sumcheck) equals b (merging of 6 and 4). xor is in hex and b is in dec value. Can i convert 64(dec) to 64(hex)?

kiran Biradar Over a year ago

@kabanos use Base 16 conversion b = ((Received[16]-'0') *16) + Received[17]-'0'; Same I have already included in the answer.

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