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diff --git a/devdocs/c/io%2Ffsetpos.html b/devdocs/c/io%2Ffsetpos.html new file mode 100644 index 00000000..3ef15100 --- /dev/null +++ b/devdocs/c/io%2Ffsetpos.html @@ -0,0 +1,73 @@ + <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> |