hex conversion madness

After doing a little thinking about the "accessing memory" discussion, etc. I thought I had the solution (but you might be able to understand this without reading that).

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int translate_lilend (int LE, int size) {
        short int len=size*2, i, letr[size];
        char hex[len+1], chr[3];
        printf("%d\t%d\n",LE,size);
        sprintf(hex, "%x\n",LE);
        for (i=0;i<len;i+=2){
                chr[0]=hex[len-(2+i)];
                chr[1]=hex[len-(1+i)];
                chr[3]=0;
                puts(chr);
                letr[i/2]=0;
                letr[i/2]=strtol(chr,NULL,16);
                printf("%d\t%d\n", i/2,letr[i/2]);
        }   
        for (i=0;i<size;i++) printf("letr:%d\n",letr[i]);
        for (i=0;i<size;i++) hex[i]=letr[i];
        hex[i+1]=0;
        puts(hex);
}
                   
         
int main(void) {
        translate_lilend(1952540788,4);  // a word is 4-bytes
}

Now, I would have thought the output from this would be consistent, even if I had some bit wrong. Instead,

Code:

1952540788      4
74
0       116
68
1       104
61
2       97
74
3       116             up to here, everything good, stays the same-- then
letr:-4108           suddenly, the array has changed!  And it's different every time the 
letr:18342          program is run!
letr:-17248
letr:18321
����6

Nb. I've done very little work with numerical arrays thus far in my learning. What's wrong?

Interesting. After I fix chr[3] = 0 to chr[2] = 0, I get:

Code:

1952540788      4
74
0       116
68
1       104
61
2       97
74
3       116
letr:116
letr:104
letr:97
letr:116
that6

which seems more consistent. (The last 6 is because you do a ++i in the for loop and then set the null character at i+1.) I don't see any reason to get what you get, but I'll keep thinking.

Originally Posted by tabstop

fix chr[3] = 0 to chr[2] = 0

Sometimes the answer is just too simple to find


And I imagine since chr wasn't assigned 4 elements, chr[3] was overwriting some part of something else, variably and repeatedly...