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📄 王大刚--c语言编程宝典--a.htm

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      <P>函数名: abort <BR>功&nbsp; 能: 异常终止一个进程 <BR>用&nbsp; 法: void abort(void); 
      <BR>程序例: <BR>#include &lt;stdio.h&gt; <BR>#include &lt;stdlib.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp; printf("Calling abort()\n"); <BR>&nbsp; 
      abort(); <BR>&nbsp; return 0; /* This is never reached */ <BR>} <BR>&nbsp; 
      <BR>&nbsp; <BR>
      <P>函数名: abs <BR>功&nbsp; 能: 求整数的绝对值 <BR>用&nbsp; 法: int abs(int i); <BR>程序例: 
      <BR>#include &lt;stdio.h&gt; <BR>#include &lt;math.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp; int number = -1234; <BR>
      <P>&nbsp; printf("number: %d&nbsp; absolute value: %d\n", number, 
      abs(number)); <BR>&nbsp; return 0; <BR>} <BR>&nbsp; <BR>&nbsp; <BR>
      <P>函数名: absread, abswirte <BR>功&nbsp; 能: 绝对磁盘扇区读、写数据 <BR>用&nbsp; 法: int 
      absread(int drive, int nsects, int sectno, void *buffer); <BR>&nbsp;int 
      abswrite(int drive, int nsects, in tsectno, void *buffer); <BR>程序例: <BR>/* 
      absread example */ <BR>
      <P>#include &lt;stdio.h&gt; <BR>#include &lt;conio.h&gt; <BR>#include 
      &lt;process.h&gt; <BR>#include &lt;dos.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp; int i, strt, ch_out, sector; <BR>&nbsp; 
      char buf[512]; <BR>
      <P>&nbsp; printf("Insert a diskette into drive A and press any key\n"); 
      <BR>&nbsp; getch(); <BR>&nbsp; sector = 0; <BR>&nbsp; if (absread(0, 1, 
      sector, &amp;buf) != 0) <BR>&nbsp; { <BR>&nbsp;&nbsp;&nbsp;&nbsp; 
      perror("Disk problem"); <BR>&nbsp;&nbsp;&nbsp;&nbsp; exit(1); <BR>&nbsp; } 
      <BR>&nbsp; printf("Read OK\n"); <BR>&nbsp; strt = 3; <BR>&nbsp; for (i=0; 
      i&lt;80; i++) <BR>&nbsp; { <BR>&nbsp;&nbsp;&nbsp;&nbsp; ch_out = 
      buf[strt+i]; <BR>&nbsp;&nbsp;&nbsp;&nbsp; putchar(ch_out); <BR>&nbsp; } 
      <BR>&nbsp; printf("\n"); <BR>&nbsp; return(0); <BR>} <BR>&nbsp; <BR>&nbsp; 
      <BR>&nbsp; <BR>
      <P>函数名: access <BR>功&nbsp; 能: 确定文件的访问权限 <BR>用&nbsp; 法: int access(const 
      char *filename, int amode); <BR>程序例: <BR>#include &lt;stdio.h&gt; 
      <BR>#include &lt;io.h&gt; <BR>
      <P>int file_exists(char *filename); <BR>
      <P>int main(void) <BR>{ <BR>&nbsp; printf("Does NOTEXIST.FIL exist: %s\n", 
      <BR>&nbsp; file_exists("NOTEXISTS.FIL") ? "YES" : "NO"); <BR>&nbsp; return 
      0; <BR>} <BR>
      <P>int file_exists(char *filename) <BR>{ <BR>&nbsp; return 
      (access(filename, 0) == 0); <BR>} <BR>&nbsp; <BR>
      <P>函数名: acos <BR>功&nbsp; 能: 反余弦函数 <BR>用&nbsp; 法: double acos(double x); 
      <BR>程序例: <BR>#include &lt;stdio.h&gt; <BR>#include &lt;math.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp; double result; <BR>&nbsp; double x = 
      0.5; <BR>
      <P>&nbsp; result = acos(x); <BR>&nbsp; printf("The arc cosine of %lf is 
      %lf\n", x, result); <BR>&nbsp; return 0; <BR>} <BR>&nbsp; <BR>&nbsp; <BR>
      <P>函数名: allocmem <BR>功&nbsp; 能: 分配DOS存储段 <BR>用&nbsp; 法: int 
      allocmem(unsigned size, unsigned *seg); <BR>程序例: <BR>#include 
      &lt;dos.h&gt; <BR>#include &lt;alloc.h&gt; <BR>#include &lt;stdio.h&gt; 
      <BR>
      <P>int main(void) <BR>{ <BR>&nbsp; unsigned int size, segp; <BR>&nbsp; int 
      stat; <BR>
      <P>&nbsp; size = 64; /* (64 x 16) = 1024 bytes */ <BR>&nbsp; stat = 
      allocmem(size, &amp;segp); <BR>&nbsp; if (stat == -1) 
      <BR>&nbsp;&nbsp;&nbsp;&nbsp; printf("Allocated memory at segment: %x\n", 
      segp); <BR>&nbsp; else <BR>&nbsp;&nbsp;&nbsp;&nbsp; printf("Failed: 
      maximum number of paragraphs available is %u\n", 
      <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
      stat); <BR>
      <P>&nbsp; return 0; <BR>} <BR>&nbsp; <BR>&nbsp; <BR>
      <P>函数名: arc <BR>功&nbsp; 能: 画一弧线 <BR>用&nbsp; 法: void far arc(int x, int y, 
      int stangle, int endangle, int radius); <BR>程序例: <BR>#include 
      &lt;graphics.h&gt; <BR>#include &lt;stdlib.h&gt; <BR>#include 
      &lt;stdio.h&gt; <BR>#include &lt;conio.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp;&nbsp;&nbsp; /* request auto detection 
      */ <BR>&nbsp;&nbsp; int gdriver = DETECT, gmode, errorcode; 
      <BR>&nbsp;&nbsp; int midx, midy; <BR>&nbsp;&nbsp; int stangle = 45, 
      endangle = 135; <BR>&nbsp;&nbsp; int radius = 100; <BR>
      <P>&nbsp;&nbsp; /* initialize graphics and local variables */ 
      <BR>&nbsp;&nbsp; initgraph(&amp;gdriver, &amp;gmode, ""); <BR>
      <P>&nbsp;&nbsp; /* read result of initialization */ <BR>&nbsp;&nbsp; 
      errorcode = graphresult();&nbsp;&nbsp;&nbsp; /* an error occurred */ 
      <BR>&nbsp;&nbsp; if (errorcode != grOk) <BR>&nbsp;&nbsp; { 
      <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; printf("Graphics error: %s\n", 
      grapherrormsg(errorcode)); <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
      printf("Press any key to halt:"); <BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
      getch(); <BR>
      <P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; exit(1);&nbsp;&nbsp;&nbsp; /* terminate 
      with an error code */ <BR>&nbsp;&nbsp; } <BR>
      <P>&nbsp;&nbsp; midx = getmaxx() / 2; <BR>&nbsp;&nbsp; midy = getmaxy() / 
      2; <BR>&nbsp;&nbsp; setcolor(getmaxcolor()); <BR>
      <P>&nbsp;&nbsp; /* draw arc */ <BR>&nbsp;&nbsp; arc(midx, midy, stangle, 
      endangle, radius); <BR>
      <P>&nbsp;&nbsp; /* clean up */ <BR>&nbsp;&nbsp; getch(); <BR>&nbsp;&nbsp; 
      closegraph(); <BR>&nbsp;&nbsp; return 0; <BR>} <BR>&nbsp; <BR>&nbsp; <BR>
      <P>函数名: asctime <BR>功&nbsp; 能: 转换日期和时间为ASCII码 <BR>用&nbsp; 法: char 
      *asctime(const struct tm *tblock); <BR>程序例: <BR>#include &lt;stdio.h&gt; 
      <BR>#include &lt;string.h&gt; <BR>#include &lt;time.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp;&nbsp; struct tm t; <BR>&nbsp;&nbsp; 
      char str[80]; <BR>
      <P>&nbsp;&nbsp; /* sample loading of tm structure&nbsp; */ <BR>
      <P>&nbsp;&nbsp; t.tm_sec&nbsp;&nbsp;&nbsp; = 1;&nbsp; /* Seconds */ 
      <BR>&nbsp;&nbsp; t.tm_min&nbsp;&nbsp;&nbsp; = 30; /* Minutes */ 
      <BR>&nbsp;&nbsp; t.tm_hour&nbsp;&nbsp; = 9;&nbsp; /* Hour */ 
      <BR>&nbsp;&nbsp; t.tm_mday&nbsp;&nbsp; = 22; /* Day of the Month&nbsp; */ 
      <BR>&nbsp;&nbsp; t.tm_mon&nbsp;&nbsp;&nbsp; = 11; /* Month */ 
      <BR>&nbsp;&nbsp; t.tm_year&nbsp;&nbsp; = 56; /* Year - does not include 
      century */ <BR>&nbsp;&nbsp; t.tm_wday&nbsp;&nbsp; = 4;&nbsp; /* Day of the 
      week&nbsp; */ <BR>&nbsp;&nbsp; t.tm_yday&nbsp;&nbsp; = 0;&nbsp; /* Does 
      not show in asctime&nbsp; */ <BR>&nbsp;&nbsp; t.tm_isdst&nbsp; = 0;&nbsp; 
      /* Is Daylight SavTime; does not show in asctime */ <BR>
      <P>&nbsp;&nbsp; /* converts structure to null terminated <BR>&nbsp;&nbsp; 
      string */ <BR>
      <P>&nbsp;&nbsp; strcpy(str, asctime(&amp;t)); <BR>&nbsp;&nbsp; 
      printf("%s\n", str); <BR>
      <P>&nbsp;&nbsp; return 0; <BR>} <BR>&nbsp; <BR>&nbsp; <BR>&nbsp; <BR>
      <P>函数名: asin <BR>功&nbsp; 能: 反正弦函数 <BR>用&nbsp; 法: double asin(double x); 
      <BR>程序例: <BR>#include &lt;stdio.h&gt; <BR>#include &lt;math.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp;&nbsp; double result; <BR>&nbsp;&nbsp; 
      double x = 0.5; <BR>
      <P>&nbsp;&nbsp; result = asin(x); <BR>&nbsp;&nbsp; printf("The arc sin of 
      %lf is %lf\n", x, result); <BR>&nbsp;&nbsp; return(0); <BR>} <BR>&nbsp; 
      <BR>&nbsp; <BR>&nbsp; <BR>
      <P>函数名: assert <BR>功&nbsp; 能: 测试一个条件并可能使程序终止 <BR>用&nbsp; 法: void 
      assert(int test); <BR>程序例: <BR>#include &lt;assert.h&gt; <BR>#include 
      &lt;stdio.h&gt; <BR>#include &lt;stdlib.h&gt; <BR>
      <P>struct ITEM { <BR>&nbsp;&nbsp; int key; <BR>&nbsp;&nbsp; int value; 
      <BR>}; <BR>
      <P>/* add item to list, make sure list is not null */ <BR>void 
      additem(struct ITEM *itemptr) { <BR>&nbsp;&nbsp; assert(itemptr != NULL); 
      <BR>&nbsp;&nbsp; /* add item to list */ <BR>} <BR>
      <P>int main(void) <BR>{ <BR>&nbsp;&nbsp; additem(NULL); <BR>&nbsp;&nbsp; 
      return 0; <BR>} <BR>&nbsp; <BR>&nbsp; <BR>&nbsp; <BR>
      <P>函数名: atan <BR>功&nbsp; 能: 反正切函数 <BR>用&nbsp; 法: double atan(double x); 
      <BR>程序例: <BR>#include &lt;stdio.h&gt; <BR>#include &lt;math.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp;&nbsp; double result; <BR>&nbsp;&nbsp; 
      double x = 0.5; <BR>
      <P>&nbsp;&nbsp; result = atan(x); <BR>&nbsp;&nbsp; printf("The arc tangent 
      of %lf is %lf\n", x, result); <BR>&nbsp;&nbsp; return(0); <BR>} <BR>&nbsp; 
      <BR>&nbsp; <BR>
      <P>函数名: atan2 <BR>功&nbsp; 能: 计算Y/X的反正切值 <BR>用&nbsp; 法: double atan2(double 
      y, double x); <BR>程序例: <BR>#include &lt;stdio.h&gt; <BR>#include 
      &lt;math.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp;&nbsp; double result; <BR>&nbsp;&nbsp; 
      double x = 90.0, y = 45.0; <BR>
      <P>&nbsp;&nbsp; result = atan2(y, x); <BR>&nbsp;&nbsp; printf("The arc 
      tangent ratio of %lf is %lf\n", (y / x), result); <BR>&nbsp;&nbsp; return 
      0; <BR>} <BR>&nbsp; <BR>&nbsp; <BR>
      <P>函数名: atexit <BR>功&nbsp; 能: 注册终止函数 <BR>用&nbsp; 法: int atexit(atexit_t 
      func); <BR>程序例: <BR>#include &lt;stdio.h&gt; <BR>#include &lt;stdlib.h&gt; 
      <BR>
      <P>void exit_fn1(void) <BR>{ <BR>&nbsp;&nbsp; printf("Exit function #1 
      called\n"); <BR>} <BR>
      <P>void exit_fn2(void) <BR>{ <BR>&nbsp;&nbsp; printf("Exit function #2 
      called\n"); <BR>} <BR>
      <P>int main(void) <BR>{ <BR>&nbsp;&nbsp; /* post exit function #1 */ 
      <BR>&nbsp;&nbsp; atexit(exit_fn1); <BR>&nbsp;&nbsp; /* post exit function 
      #2 */ <BR>&nbsp;&nbsp; atexit(exit_fn2); <BR>&nbsp;&nbsp; return 0; <BR>} 
      <BR>&nbsp; <BR>&nbsp; <BR>&nbsp; <BR>
      <P>函数名: atof <BR>功&nbsp; 能: 把字符串转换成浮点数 <BR>用&nbsp; 法: double atof(const 
      char *nptr); <BR>程序例: <BR>#include &lt;stdlib.h&gt; <BR>#include 
      &lt;stdio.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp;&nbsp; float f; <BR>&nbsp;&nbsp; char 
      *str = "12345.67"; <BR>
      <P>&nbsp;&nbsp; f = atof(str); <BR>&nbsp;&nbsp; printf("string = %s float 
      = %f\n", str, f); <BR>&nbsp;&nbsp; return 0; <BR>} <BR>&nbsp; <BR>&nbsp; 
      <BR>
      <P>函数名: atoi <BR>功&nbsp; 能: 把字符串转换成长整型数 <BR>用&nbsp; 法: int atoi(const char 
      *nptr); <BR>程序例: <BR>#include &lt;stdlib.h&gt; <BR>#include 
      &lt;stdio.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp;&nbsp; int n; <BR>&nbsp;&nbsp; char *str 
      = "12345.67"; <BR>
      <P>&nbsp;&nbsp; n = atoi(str); <BR>&nbsp;&nbsp; printf("string = %s 
      integer = %d\n", str, n); <BR>&nbsp;&nbsp; return 0; <BR>} <BR>&nbsp; 
      <BR>&nbsp; <BR>
      <P>函数名: atol <BR>功&nbsp; 能: 把字符串转换成长整型数 <BR>用&nbsp; 法: long atol(const 
      char *nptr); <BR>程序例: <BR>
      <P>#include &lt;stdlib.h&gt; <BR>#include &lt;stdio.h&gt; <BR>
      <P>int main(void) <BR>{ <BR>&nbsp;&nbsp; long l; <BR>&nbsp;&nbsp; char 
      *str = "98765432"; <BR>
      <P>&nbsp;&nbsp; l = atol(lstr); <BR>&nbsp;&nbsp; printf("string = %s 
      integer = %ld\n", str, l); <BR>&nbsp;&nbsp; return(0); <BR>} <BR>&nbsp; 
      <BR>
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