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copied!<p>Pascal was originally designed as a teaching language to encourage block-structured programming. Kernighan (the K of K&R) wrote an (understandably biased) essay on Pascal's limitations, <a href="http://www.lysator.liu.se/c/bwk-on-pascal.html" rel="nofollow noreferrer"><em>Why Pascal is Not My Favorite Programming Language</em></a>.</p> <p>The prohibition on modifying what Pascal calls the <em>control variable</em> of a <code>for</code> loop, combined with the lack of a <code>break</code> statement means that it is possible to know how many times the loop body is executed without studying its contents.</p> <p>Without a <code>break</code> statement, and not being able to use the control variable after the loop terminates is more of a restriction than not being able to modify the control variable inside the loop as it prevents some string and array processing algorithms from being written in the "obvious" way.</p> <p>These and other difference between Pascal and C reflect the different philosophies with which they were first designed: Pascal to enforce a concept of "correct" design, C to permit more or less anything, no matter how dangerous.</p> <p>(Note: Delphi does have a <code>Break</code> statement however, as well as <code>Continue</code>, and <code>Exit</code> which is like <code>return</code> in C.)</p> <p>Clearly we never <strong>need</strong> to be able to modify the control variable in a <code>for</code> loop, because we can always rewrite using a <code>while</code> loop. An example in C where such behaviour is used can be found in K&R section 7.3, where a simple version of <code>printf()</code> is introduced. The code that handles <code>'%'</code> sequences within a format string <code>fmt</code> is:</p> <pre><code>for (p = fmt; *p; p++) { if (*p != '%') { putchar(*p); continue; } switch (*++p) { case 'd': /* handle integers */ break; case 'f': /* handle floats */ break; case 's': /* handle strings */ break; default: putchar(*p); break; } } </code></pre> <p>Although this uses a pointer as the loop variable, it could equally have been written with an integer index into the string:</p> <pre><code>for (i = 0; i < strlen(fmt); i++) { if (fmt[i] != '%') { putchar(fmt[i]); continue; } switch (fmt[++i]) { case 'd': /* handle integers */ break; case 'f': /* handle floats */ break; case 's': /* handle strings */ break; default: putchar(fmt[i]); break; } } </code></pre>

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