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  1. PO
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    <p>Some people will object to this, but I think in these situations a plain old <code>goto</code> is a very clean and readable way of doing things, because it emphasizes the linearity of the "normal" control path:</p> <pre><code>int main(int arg, char *argv[]) { int choice; choose_shape: printf("Choose a shape from the following:\n" " 1.Sphere\n 2.Cone\n 3.Cylinder\n"); scanf("%d", &amp;choice); if (choice &lt; 1 || choice &gt; 3) { printf("Invalid selection, please choose again.\n"); goto choose_shape; } printf("Enter the radius, r:\n"); ... } </code></pre> <p>Yes, people have complained about <code>goto</code> so let me justify it some more.</p> <p>Here is a more sophisticated version that allows you to select a shape by letter:</p> <pre><code> char c; shape_t shape; choose_shape: printf("Choose a shape: [s]phere, [c]one, c[y]linder:\n"); scanf("%c", &amp;c); switch (c) { cases 's': shape = SHAPE_SPHERE; break; case 'c': shape = SHAPE_CONE; break; case 'y': shape = SHAPE_CYLINDER; break; default: printf("Not a valid shape: %c\n", c); goto choose_shape; } </code></pre> <p>And here is the version with <code>goto</code>. Note that this introduces another variable, <code>flag</code>, whose only purpose is to get rid of the <code>goto</code> statement. You cannot simply use <code>break</code> here (which is an unlabeled <code>goto</code> to begin with) because of the <code>switch</code> statement. I consider this harder to read due to the additional state. It's five lines longer.</p> <pre><code> char c; shape_t shape; int flag; for (flag = 0; !flag; ) { printf("Choose a shape: [s]phere, [c]one, c[y]linder:\n"); scanf("%c", &amp;c); switch (c) { cases 's': shape = SHAPE_SPHERE; flag = 1; break; case 'c': shape = SHAPE_CONE; flag = 1; break; case 'y': shape = SHAPE_CYLINDER; flag = 1; break; default: printf("Not a valid shape: %c\n", c); break; } } </code></pre>
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    1. POInput validation in C
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    1. USDietrich Epp
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    1. COPlease don't use goto.
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      1. USDesert Ice
    2. COusing goto is bad practice
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      1. USRavindra Bagale
    3. CO@DesertIce: If you can't articulate why not to use `goto`, then you're just repeating what someone told you.
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      1. USDietrich Epp
 

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