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POMulti-dimensional char array prints within function, but not when passed to another function
 

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  1. POMulti-dimensional char array prints within function, but not when passed to another function
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    <p>I am attempting to write data into a multi-dimensional array, and then pass the array as a <code>const char**</code> to another function. When I print the <code>char*</code> locally in the function in which it is declared, everything works as expected. But, when I try to print the array of <code>char*</code> in another function, they are all empty strings. </p> <p>I am using the following code:</p> <pre><code>void my_print (const char** lines, unsigned int num) { int i = 0; for (i = 0; i &lt; num; i++) { fprintf(stderr, "lines[%d]: %s", i, lines[i]); } } void my_func () { char cfg[2][200]; unsigned int value = 5; snprintf(cfg[0], 200, "one two three\n"); snprintf(cfg[1], 200, "my value = %u\n", value); fprintf(stderr, "lines[0] = %slines[1] = %s\n", cfg[0], cfg[1]); my_print((const char**) cfg, 2); } </code></pre> <p>This results in the following output:</p> <pre><code>lines[0] = one two three lines[1] = my value = 5 lines[0]: lines[1]: </code></pre> <p>If instead, of the given <code>my_func</code>, I use the following:</p> <pre><code>void my_func () { char* cfg[2]; unsigned int value = 5; cfg[0] = malloc(200); cfg[1] = malloc(200); snprintf(cfg[0], 200, "one two three\n"); snprintf(cfg[1], 200, "my value = %u\n", value); fprintf(stderr, "lines[0] = %slines[1] = %s\n", cfg[0], cfg[1]); my_print((const char**) cfg, 2); } </code></pre> <p>Then, everything works, and I get:</p> <pre><code>lines[0] = one two three lines[1] = my value = 5 lines[0]: one two three lines[1]: my value = 5 </code></pre> <p>So, what is happening in the background here? Why do I need to use <code>malloc</code> in order for <code>my_print</code> to be able to print my strings?</p> <p>Thanks you</p>
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