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POWhy is the %n format specifier working normal for all scanf() statements but storing one less in the first one?
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copied!<p>The <code>%n</code> format specifier,when used in a <code>scanf()</code> is expected to store the count of the number of characters of the format string already processed by the function into an argument of type <code>int*</code>.According to the definition:</p> <p><code>The number of characters of the format string already processed is stored in the pointed location.</code></p> <p>But in my program,it works so in all but the first <code>scanf()</code>.In all <code>scanf()</code>s in my program,excluding the first one,it stores the count of the total number of characters entered from the console,including the newlines (<strong>Enter</strong> keys).But in the first <code>scanf()</code>, the count is <strong>one less than</strong> the total count of characters and newlines entered from the console.</p> <p>Please explain this anomaly as it's really frustrating that I can't detect this simple bug.</p> <pre><code>#include <stdio.h> int main () { int a,b,c,d,count; printf("First Trial\n"); scanf("%d%d%d%d%n",&a,&b,&c,&d,&count); //OUTPUT ANOMALY HERE printf("count=%d\n",count); printf("Second Trial\n"); scanf("%d%n",&a,&count); printf("count=%d\n",count); printf("Third Trial\n"); scanf("%d%d%n",&a,&b,&count); printf("count=%d\n",count); printf("Fourth Trial\n"); scanf("%d%n%d",&a,&count,&b); printf("count=%d",count); } </code></pre> <p><strong>Sample Output</strong></p> <pre><code>First Trial 253 34 4 83 count=11 Second Trial 25 count=3 Third Trial 234 38 count=7 Fourth Trial 3534 35 count=5 </code></pre> <p><strong>Why in the first trial we get "11" instead of "12</strong>?That's my doubt.</p> <p><strong>CRUCIAL EDIT</strong></p> <p>Another finding.If for the first <code>scanf()</code>,instead of using <code>Enter</code> keys(newlines) to separate the numbers entered, if I use space,lots of whitespace,then all those whitespace are counted by <code>count</code> as well.For example I get <code>count=21</code>.It means the newlines,spaces,everything is being considered.But why it is <strong>one less</strong> for first trial?</p> <pre><code>First Trial 25 35 38 98 count=21 </code></pre>

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