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copied!<ol> <li><p>One serious problem here is</p> <pre><code>char cont[] = { 'y' }; ... s("%s", &cont[0]); </code></pre> <p>You've only reserved <strong>one</strong> byte but <code>scanf</code> will write at least 2 bytes, meaning that you are going to have a buffer overflow and then the overall behaviour is unpredictable. If you want to read a single character then use<code>"%c"</code> as a pattern but the problem here is that characters will be in the buffer for the next read, so you are going to have to clear the buffer.</p> <p>It's much easier to do:</p> <pre><code>char line[1024]; fgets(line, sizeof line, stdin); if(line[strlen(line)-1] == '\n') line[strlen(line)-1] = 0; if(strcmp(line, "Y") == 0 || strcmp(line, "y")==0) </code></pre> <p>It's a little more code but it's safer this way.</p></li> <li><p>There are many queues, there are fifo, lifo, and depending on it you choose how to build it</p></li> <li><p>When dealing with queues, it's better to use function names like <code>push</code>, <code>pop</code> and <code>top</code> because they are widely used among other programmers and queue libraries. Use these names instead.</p></li> <li><p>In your case, instead if remembering with <code>front</code> and <code>rear</code> you should use <code>memmove</code> instead and use a variable <code>len</code> to count the current number of elements in the node. Once you've popped one element, you gained new space for more elements.</p></li> </ol> <p>Also, try to use fewer global variables and more encapsulation: (in my example I am not going to care about <code>malloc</code> returning <code>NULL</code>, I want to keep it short)</p> <pre><code>#include <string.h> /* for size_t */ typefed struct { size_z len; size_z max_size; int *data; } queue; void queue_init(queue *q, size_t max_size) { q->len = 0; q->max_size = max_size; q->data = malloc(max_size * sizeof *(q->data)); /* this is a good trick! * If you need to change the datatype of 'data', * you only need to change the definition of it. * This code is valid for any type */ } int push(queue *q, int data) { if(q->len == q->max_size) return 0; /* not enough space */ q->data[q->len++] = data; return 1; } int top(queue *q, int *data) { if(q->len == 0) return 0; /* no elements in the queue */ *data = q->data[0]; return 1; } int pop(queue *q, int *data) { if(top(q, data) == 0) return 0; memmove(q->data, q->data + sizeof *(q->data), q->len--); return 1; } </code></pre> <p>BTW:</p> <pre><code>#define p printf #define s scanf </code></pre> <p>Just like Daniel Fischer said, this is ugly; don't do that.</p>

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