I have this small exercise that I am trying to finish, but I get an error that I’ve never seen before. It doesn’t even seem logical to me:
Unhandled exception at 0x0003191a in oop244_a1.exe: 0xC0000005: Access violation reading location 0x003134d4.
Here is the program code:
The function is at the button (bit_to_ascii), that is where the problem is occuring. I’ve tried debugging the program, and it seems that the variable ‘clen’ gets changed for some reason, to a unreasonably high number (100000+), when its supposed to be 950 characters for that loop
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <math.h>
#define LINES 5
/* assignment #1 function prototype */
int bit_to_ascii(const char [ ], char [ ]);
int main( ) {
const char *core_data[ ] = {
"0", /* should insert the null byte '\0' only */
"01010111 This sequence contains the letter 'W' " /* 87 = 'W' */
" r5 0 #! 1 1 gP 0 f66-:] 0 [ } 1 v4t^ 0 1 n>?:77" /* 101 = 'e' */
" junk ^*@&#^% 0110 more junk }{r;,<> 1100 2x" /* 108 = 'l' */
" 0 1 1 0 0 011" /* 99 = 'c' */
"0 ^%jh 1 ]{) OVR 1 - 0 _! 9 + 1 118Y z(x pM1 " /* 111 = 'o' */
"This next group of 8 should be SKP skipped! 11111111 " /* skipped */
"*&^! 0 1 1 0 1 1 0 128673kjshd:L< 2938 " /* 109 = 'm' */
" r5 0 #! 1 1 gP 0 f66-:] 0 [ } 1 v4t^ 0 1 n>?:77" /* 101 = 'e' */
"#!/bin/bash 00 1 00 00 0 g^b-ps 6@&^% " /* 32 = ' ' */
"01010100 This sequence contains the letter 'T' " /* 84 = 'T' */
"0 ^%jh 1 ]{) OVR 1 - 0 _! 9 + 1 118Y z(x pM1 " /* 111 = 'o' */
"#!/bin/bash 00 1 00 00 0 g^b-ps 6@&^% " /* 32 = ' ' */
"---repeat--->0 1 0 0 1 1 1 1<------------RPT2--------" /* 79 = 'O' */
"0 1 0 1 0bbavac9872962 000&*************************" /* 80 = 'P' */
"a0b0c1d1e0f0g1h0ijklmnopqrstuvwxyz*******************" /* 50 = '2' */
"00fg333 110100>>>>>>>>" /* 52 = '4' */
"00fg333 110100>>>>>>>>" /* 52 = '4' */
" 0000 ",/* 0 = '\0' */
"00011110 This char should not be inserted! " /* 30 cntrl */
" 00011111 This char should not be inserted! " /* 31 cntrl */
" 00100000 " /* 32 = ' ' */
" 00100001 " /* 33 = '!' */
" 00100010 " /* 34 = '"' */
" 00100011 " /* 35 = '#' */
" 00100100 " /* 36 = '$' */
" 00100101 " /* 37 = '%' */
" 00100110 " /* 38 = '&' */
" 00100111 " /* 39 = ''' */
" 00101000 " /* 40 = '(' */
" 00101001 " /* 41 = ')' */
" 00101010 " /* 42 = '*' */
" 00101011 " /* 43 = '+' */
" 00101100 " /* 44 = ',' */
" 00101101 " /* 45 = '-' */
" 00101110 " /* 46 = '.' */
" 00101111 " /* 47 = '/' */
" 00110000 " /* 48 = '0' */
" 00110001 " /* 49 = '1' */
" 00110010 " /* 50 = '2' */
" 00110011 " /* 51 = '3' */
" 00110100 " /* 52 = '4' */
" 00110101 " /* 53 = '5' */
" 00110110 " /* 54 = '6' */
" 00110111 " /* 55 = '7' */
" 00111000 " /* 56 = '8' */
" 00111001 " /* 57 = '9' */
" 00111010 " /* 58 = ':' */
" 00111011 " /* 59 = ';' */
" 00111100 " /* 60 = '<' */
" 00111101 " /* 61 = '=' */
" 00111110 " /* 62 = '>' */
" 00111111 " /* 63 = '?' */
" 01000000 " /* 64 = '@' */
" 00000000 ",/* 0 = '\0'*/
" 01000001 " /* 65 = 'A' */
" 01000010 " /* 66 = 'B' */
" 01000011 " /* 67 = 'C' */
" 01000100 " /* 68 = 'D' */
" 01000101 " /* 69 = 'E' */
" 01000110 " /* 70 = 'F' */
" 01000111 " /* 71 = 'G' */
" 01001000 " /* 72 = 'H' */
" 01001001 " /* 73 = 'I' */
" 01001010" /* 74 = 'J' */
" 01001011 " /* 75 = 'K' */
" 01001100 " /* 76 = 'L' */
" 01001101 " /* 77 = 'M' */
" 01001110 " /* 78 = 'N' */
" 01001111 " /* 79 = 'O' */
" 01010000 " /* 80 = 'P' */
" 01010001 " /* 81 = 'Q' */
" 01010010 " /* 82 = 'R' */
" 01010011 " /* 83 = 'S' */
" 01010100 " /* 84 = 'T' */
" 01010101 " /* 85 = 'U' */
" 01010110 " /* 86 = 'V' */
" 01010111 " /* 87 = 'W' */
" 01011000 " /* 88 = 'X' */
" 01011001 " /* 89 = 'Y' */
" 01011010 " /* 90 = 'Z' */
" 01011011 " /* 91 = '[' */
" 01011100 " /* 92 = '/' */
" 01011101 " /* 93 = ']' */
" 01011110 " /* 94 = '^' */
" 01011111 " /* 95 = '_' */
" 01100000 " /* 96 = '`' */
" 00000000 ",/* 0 = '\0'*/
" 01100001 " /* 97 = 'a' */
" 01100010 " /* 98 = 'b' */
" 01100011 " /* 99 = 'c' */
" 01100100 " /* 100 = 'd' */
" 01100101 " /* 101 = 'e' */
" 01100110 " /* 102 = 'f' */
" 01100111 " /* 103 = 'g' */
" 01101000 " /* 104 = 'h' */
" 01101001 " /* 105 = 'i' */
" 01101010 " /* 106 = 'j' */
" 01101011 " /* 107 = 'k' */
" 01101100 " /* 108 = 'l' */
" 01101101 " /* 109 = 'm' */
" 01101110 " /* 110 = 'n' */
" 01101111 " /* 111 = 'o' */
" 01110000 " /* 112 = 'p' */
" 01110001 " /* 113 = 'q' */
" 01110010 " /* 114 = 'r' */
" 01110011 " /* 115 = 's' */
" 01110100 " /* 116 = 't' */
" 01110101 " /* 117 = 'u' */
"01110110 " /* 118 = 'v' */
" 01110111 " /* 119 = 'w' */
" 01111000 " /* 120 = 'x' */
" 01111001 " /* 121 = 'y' */
" 01111010 " /* 122 = 'z' */
" 01111011 " /* 123 = '{' */
" 011111RPT10 " /* 124 = '|' */
" 01111101 " /* 125 = '}' */
" 00000000 " /* 0 = '\0'*/
};
char phrase[41];
char correct[LINES][41] = {
"",
"Welcome To OOP244",
" !\"#$%&'()*+,-./0123456789:;<=>?@",
"ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`",
"abcdefghijklmnopqrstuvwxyz{||||||||||}"
};
int rvalues[LINES] = { 1, 18, 34, 33, 39 }, i;
int valid = 1, rc, err_code;
for(i=0; i<LINES && valid; i++) {
rc = bit_to_ascii(core_data[i], phrase);
if(rc != rvalues[i] || strcmp(phrase, correct[i])) {
printf("Failed on test... %d\n\n", i+1);
valid = 0;
}
else {
printf("Passed test %d...\n\n", i+1);
}
printf("Your string ----------> '%s'\n", phrase);
printf("Actual string --------> '%s'\n", correct[i]);
printf("Your return value ----> %d\n", rc);
printf("Actual return value --> %d\n", rvalues[i]);
printf("Press the ENTER key to continue...");
getchar( );
}
if(valid) {
printf("\nCongratualtions!!! You passed all tests.\n");
printf("You may hand in your assignment.\n");
}
else {
printf("\nYou correctly sequenced %d/5 data blocks...\n", i-1);
printf("Your program still needs some work!\n");
printf("Keep at it!\n\n");
}
getchar();
return 0;
}
int bit_to_ascii(const char core[], char data[]) {
int clen = strlen(core);
int dlen = strlen(data);
char bits[8] = {0,0,0,0,0,0,0,0};
int bit_idx = 0;
int i = 0;
int dcount = 0;
printf("clen: %d\n", clen);
for (i = 0; i < clen; i++) {
if (core[i] == '0' || core[i] == '1') {
bits[bit_idx++] = core[i];
//printf("bit_idx: %d\n", bit_idx);
//printf("clen: %d\n", clen);
//printf("i+1: %d\n", i+1);
if (bit_idx == 8 || ((i+1) >= clen)) {
int power = 7;
double dec = 0.0;
int j;
// fill in with zeroes
for (j = bit_idx; j < 8; j++) {
bits[j] = 0;
}
// binary to decimal
for (j = 0; j < 8; j++) {
if (bits[j] == '1') {
dec += pow((double)2, power--);
}
}
data[dcount++] = (int)dec;
}
}
}
return dcount;
}
I didn’t test it, but probably you have to set
bit_idxto ‘0’ after reaching8.If not, you will write out of the
bitsarray and overwrite the stack. Probably theclenvariable happens to be just there.