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<h1 id="firstHeading" class="firstHeading">wmemcmp</h1> <table class="t-dcl-begin"> <tr class="t-dsc-header"> <th> Defined in header <code><wchar.h></code> </th> <th> </th> <th> </th> </tr> <tr class="t-dcl"> <td> <pre data-language="c">int wmemcmp( const wchar_t* lhs, const wchar_t* rhs, size_t count );</pre>
</td> <td class="t-dcl-nopad"> </td> <td> <span class="t-mark-rev t-since-c95">(since C95)</span> </td> </tr> </table> <p>Compares the first <code>count</code> wide characters of the wide character (or compatible integer type) arrays pointed to by <code>lhs</code> and <code>rhs</code>. The comparison is done lexicographically.</p>
<p>The sign of the result is the sign of the difference between the values of the first pair of wide characters that differ in the arrays being compared.</p>
<p>If <code>count</code> is zero, the function does nothing.</p>
<h3 id="Parameters"> Parameters</h3> <table class="t-par-begin"> <tr class="t-par"> <td> lhs, rhs </td> <td> - </td> <td> pointers to the wide character arrays to compare </td>
</tr> <tr class="t-par"> <td> count </td> <td> - </td> <td> number of wide characters to examine </td>
</tr>
</table> <h3 id="Return_value"> Return value</h3> <p>Negative value if the value of the first differing wide character in <code>lhs</code> is less than the value of the corresponding wide character in <code>rhs</code>: <code>lhs</code> precedes <code>rhs</code> in lexicographical order.</p>
<p><code>0</code> if all <code>count</code> wide characters of <code>lhs</code> and <code>rhs</code> are equal.</p>
<p>Positive value if the value of the first differing wide character in <code>lhs</code> is greater than the value of the corresponding wide character in <code>rhs</code>: <code>rhs</code> precedes <code>lhs</code> in lexicographical order.</p>
<h3 id="Notes"> Notes</h3> <p>This function is not locale-sensitive and pays no attention to the values of the <code>wchar_t</code> objects it examines: nulls as well as invalid wide characters are compared too.</p>
<h3 id="Example"> Example</h3> <div class="t-example"> <div class="c source-c"><pre data-language="c">#include <locale.h>
#include <stdio.h>
#include <wchar.h>
void demo(const wchar_t* lhs, const wchar_t* rhs, size_t sz)
{
for (size_t n = 0; n < sz; ++n)
putwchar(lhs[n]);
int rc = wmemcmp(lhs, rhs, sz);
if (rc == 0)
wprintf(L" compares equal to ");
else if(rc < 0)
wprintf(L" precedes ");
else if(rc > 0)
wprintf(L" follows ");
for (size_t n = 0; n < sz; ++n)
putwchar(rhs[n]);
wprintf(L" in lexicographical order\n");
}
int main(void)
{
setlocale(LC_ALL, "en_US.utf8");
wchar_t a1[] = {L'α',L'β',L'γ'};
wchar_t a2[] = {L'α',L'β',L'δ'};
size_t sz = sizeof a1 / sizeof *a1;
demo(a1, a2, sz);
demo(a2, a1, sz);
demo(a1, a1, sz);
}</pre></div> <p>Output:</p>
<div class="text source-text"><pre data-language="c">αβγ precedes αβδ in lexicographical order
αβδ follows αβγ in lexicographical order
αβγ compares equal to αβγ in lexicographical order</pre></div> </div> <h3 id="References"> References</h3> <ul>
<li> C23 standard (ISO/IEC 9899:2023): </li>
<ul><li> 7.29.4.4.5 The wmemcmp function (p: TBD) </li></ul>
<li> C17 standard (ISO/IEC 9899:2018): </li>
<ul><li> 7.29.4.4.5 The wmemcmp function (p: TBD) </li></ul>
<li> C11 standard (ISO/IEC 9899:2011): </li>
<ul><li> 7.29.4.4.5 The wmemcmp function (p: 435) </li></ul>
<li> C99 standard (ISO/IEC 9899:1999): </li>
<ul><li> 7.24.4.4.5 The wmemcmp function (p: 381) </li></ul>
</ul> <h3 id="See_also"> See also</h3> <table class="t-dsc-begin"> <tr class="t-dsc"> <td> <div><a href="wcscmp" title="c/string/wide/wcscmp"> <span class="t-lines"><span>wcscmp</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span></span></div> </td> <td> compares two wide strings <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="../byte/memcmp" title="c/string/byte/memcmp"> <span class="t-lines"><span>memcmp</span></span></a></div> </td> <td> compares two buffers <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="wcsncmp" title="c/string/wide/wcsncmp"> <span class="t-lines"><span>wcsncmp</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span></span></div> </td> <td> compares a certain amount of characters from two wide strings <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td colspan="2"> <span><a href="https://en.cppreference.com/w/cpp/string/wide/wmemcmp" title="cpp/string/wide/wmemcmp">C++ documentation</a></span> for <code>wmemcmp</code> </td>
</tr> </table> <div class="_attribution">
<p class="_attribution-p">
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<a href="https://en.cppreference.com/w/c/string/wide/wmemcmp" class="_attribution-link">https://en.cppreference.com/w/c/string/wide/wmemcmp</a>
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