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POC programming: Using fread into char array - get very slightly different values from int array
 

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  1. POC programming: Using fread into char array - get very slightly different values from int array
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    <p>I've started learning C in my course and I'm having some trouble debugging a program I'm making. The program is an emulator for a simplified MIPS language and basically I'm trying to read in a binary file of 32-bit instructions and store it directly into an array so that my program can go through the instructions with a program counter. </p> <p>Anyway, in my first attempt at the program I had the memory that the file was read into as a 32-bit int array. The emulator worked fine and the results of my emulator matched the expected results. </p> <p>The specification wanted the emulator to be byte addressable however, so I changed the memory to an array of 1-byte chars. I then changed the rest of the program as appropriate so that it would make sure it read each instruction by taking 4 blocks of chars. </p> <p>In the int version of my emulator:</p> <pre><code>int loadBin(char path[]) { printf("%s\n",path); //open file FILE *fp; if ((fp = fopen(path, "rb")) == NULL) { perror("Error opening binary file"); return 1; } //read from file to memory fread(&amp;vm.memory, 4, 16384, fp); } </code></pre> <p>ANd in the char version:</p> <pre><code>int loadBin(char path[]) { //open file FILE *fp; if ((fp = fopen(path, "rb")) == NULL) { perror("Error opening binary file"); return 1; } //read from file to memory fread(&amp;vm.memory, 1, 65536, fp); fclose(fp); return 0; } </code></pre> <p>But the char memory emulator read an incorrect 32-bit instruction half way through the program. </p> <p>Using:</p> <pre><code>int test = (vm.memory[16]) + (vm.memory[17] &lt;&lt; 8) + (vm.memory[18] &lt;&lt; 16) + (vm.memory[19] &lt;&lt; 24); printf("%d\n", test); return 0; </code></pre> <p>results in a DIFFERENT number from what I get in the int array at vm.memory[4] which should be exactly the same. The results up to vm.memory[4] are the same in the char array, but for some reason something goes wrong. Can anybody help?</p> <p>Thx</p>
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      1. POC programming: Using fread into char array - get very slightly different values from int array
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    1. COIs this C or C++?
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    2. CORemoved `[c++]` tag, because this most definitly is C code and you only say "C programming" all the time.
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