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<h1 id="firstHeading" class="firstHeading">fsetpos</h1> <table class="t-dcl-begin"> <tr class="t-dsc-header"> <th> Defined in header <code><stdio.h></code> </th> <th> </th> <th> </th> </tr> <tr class="t-dcl"> <td class="t-dcl-nopad"> <pre data-language="c">int fsetpos( FILE *stream, const fpos_t *pos );</pre>
</td> <td class="t-dcl-nopad"> </td> <td class="t-dcl-nopad"> </td> </tr> </table> <p>Sets the file position indicator and the multibyte parsing state (if any) for the file stream <code>stream</code> according to the value pointed to by <code>pos</code>.</p>
<p>Besides establishing new parse state and position, a call to this function undoes the effects of <code><a href="ungetc" title="c/io/ungetc">ungetc</a></code> and clears the end-of-file state, if it is set.</p>
<p>If a read or write error occurs, the error indicator (<code><a href="ferror" title="c/io/ferror">ferror</a></code>) for the stream is set.</p>
<h3 id="Parameters"> Parameters</h3> <table class="t-par-begin"> <tr class="t-par"> <td> stream </td> <td> - </td> <td> file stream to modify </td>
</tr> <tr class="t-par"> <td> pos </td> <td> - </td> <td> pointer to a <code><a href="fpos_t" title="c/io/fpos t">fpos_t</a></code> object to use as new value of file position indicator </td>
</tr>
</table> <h3 id="Return_value"> Return value</h3> <p><code>0</code> upon success, nonzero value otherwise.</p>
<h3 id="Notes"> Notes</h3> <p>After seeking to a non-end position in a wide stream, the next call to any output function may render the remainder of the file undefined, e.g. by outputting a multibyte sequence of a different length.</p>
<h3 id="Example"> Example</h3> <div class="t-example">
<p>fsetpos with error checking</p>
<div class="c source-c"><pre data-language="c">#include <stdio.h>
#include <stdlib.h>
int main(void)
{
/* Prepare an array of f-p values. */
#define SIZE 5
double A[SIZE] = {1.,2.,3.,4.,5.};
/* Write array to a file. */
FILE * fp = fopen("test.bin", "wb");
fwrite(A,sizeof(double),SIZE,fp);
fclose (fp);
/* Read the f-p values into array B. */
double B[SIZE];
fp = fopen("test.bin","rb");
fpos_t pos;
if (fgetpos(fp,&pos) != 0) /* current position: start of file */
{
perror("fgetpos()");
fprintf(stderr,"fgetpos() failed in file %s at line # %d\n", __FILE__,__LINE__-3);
exit(EXIT_FAILURE);
}
int ret_code = fread(B,sizeof(double),1,fp); /* read one f-p value */
/* current position: after reading one f-p value */
printf("%.1f; read count = %d\n", B[0], ret_code); /* print one f-p value and ret_code */
if (fsetpos(fp,&pos) != 0) /* reset current position to start of file */
{
if (ferror(fp))
{
perror("fsetpos()");
fprintf(stderr,"fsetpos() failed in file %s at line # %d\n", __FILE__,__LINE__-5);
exit(EXIT_FAILURE);
}
}
ret_code = fread(B,sizeof(double),1,fp); /* reread first f-p value */
printf("%.1f; read count = %d\n", B[0], ret_code); /* print one f-p value and ret_code */
fclose(fp);
return EXIT_SUCCESS;
}</pre></div> <p>Output:</p>
<div class="text source-text"><pre data-language="c">1.0; read count = 1
1.0; read count = 1</pre></div> </div> <h3 id="References"> References</h3> <ul>
<li> C11 standard (ISO/IEC 9899:2011): </li>
<ul><li> 7.21.9.3 The fsetpos function (p: 337) </li></ul>
<li> C99 standard (ISO/IEC 9899:1999): </li>
<ul><li> 7.19.9.3 The fsetpos function (p: 303) </li></ul>
<li> C89/C90 standard (ISO/IEC 9899:1990): </li>
<ul><li> 4.9.9.3 The fsetpos function </li></ul>
</ul> <h3 id="See_also"> See also</h3> <table class="t-dsc-begin"> <tr class="t-dsc"> <td> <div><a href="fgetpos" title="c/io/fgetpos"> <span class="t-lines"><span>fgetpos</span></span></a></div> </td> <td> gets the file position indicator <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="ftell" title="c/io/ftell"> <span class="t-lines"><span>ftell</span></span></a></div> </td> <td> returns the current file position indicator <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="fseek" title="c/io/fseek"> <span class="t-lines"><span>fseek</span></span></a></div> </td> <td> moves the file position indicator to a specific location in a file <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/io/c/fsetpos" title="cpp/io/c/fsetpos">C++ documentation</a></span> for <code>fsetpos</code> </td>
</tr> </table> <div class="_attribution">
<p class="_attribution-p">
© cppreference.com<br>Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.<br>
<a href="https://en.cppreference.com/w/c/io/fsetpos" class="_attribution-link">https://en.cppreference.com/w/c/io/fsetpos</a>
</p>
</div>
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