函数名:?raise?

功??能:?向正在执行的程序发送一个信号?

用??法:?int?raise(int?sig);?

程序例:?

#include?<signal.h>?
int?main(void)?
{?
???int?a,?b;?
???a?=?10;?
???b?=?0;?
???if?(b?==?0)?
???/*?preempt?divide?by?zero?error?*/?
??????raise(SIGFPE);?
???a?=?a?/?b;?
???return?0;?
}?
??
??
函数名:?rand?
功??能:?随机数发生器?
用??法:?void?rand(void);?
程序例:?
#include?<stdlib.h>?
#include?<stdio.h>?
int?main(void)?
{?
???int?i;?
???printf("Ten?random?numbers?from?0?to?99\n\n");?
???for(i=0;?i<10;?i++)?
??????printf("%d\n",?rand()?%?100);?
???return?0;?
}?
??
??
函数名:?randbrd?
功??能:?随机块读?
用??法:?int?randbrd(struct?fcb?*fcbptr,?int?reccnt);?
程序例:?
#include?<process.h>?
#include?<string.h>?
#include?<stdio.h>?
#include?<dos.h>?
int?main(void)?
{?
???char?far?*save_dta;?
???char?line[80],?buffer[256];?
???struct?fcb?blk;?
???int?i,?result;?
???/*?get?user?input?file?name?for?dta?*/?
???printf("Enter?drive?and?file?name?(no?path?-?i.e.?a:file.dat)\n");?
???gets(line);?
???/*?put?file?name?in?fcb?*/?
???if?(!parsfnm(line,?&blk,?1))?
???{?
??????printf("Error?in?call?to?parsfnm\n");?
??????exit(1);?
???}?
???printf("Drive?#%d??File:?%s\n\n",?blk.fcb_drive,?blk.fcb_name);?
???/*?open?file?with?DOS?FCB?open?file?*/?
???bdosptr(0x0F,?&blk,?0);?
???/*?save?old?dta,?and?set?new?one?*/?
???save_dta?=?getdta();?
???setdta(buffer);?
???/*?set?up?info?for?the?new?dta?*/?
???blk.fcb_recsize?=?128;?
???blk.fcb_random?=?0L;?
???result?=?randbrd(&blk,?1);?
???/*?check?results?from?randbrd?*/?
???if?(!result)?
??????printf("Read?OK\n\n");?
???else?
???{?
??????perror("Error?during?read");?
??????exit(1);?
???}?
???/*?read?in?data?from?the?new?dta?*/?
???printf("The?first?128?characters?are:\n");?
???for?(i=0;?i<128;?i++)?
??????putchar(buffer[i]);?
???/*?restore?previous?dta?*/?
???setdta(save_dta);?
???return?0;?
}?
??
函数名:?randbwr?
功??能:?随机块写?
用??法:?int?randbwr(struct?fcp?*fcbptr,?int?reccnt);?
程序例:?
#include?<process.h>?
#include?<string.h>?
#include?<stdio.h>?
#include?<dos.h>?
int?main(void)?
{?
???char?far?*save_dta;?
???char?line[80];?
???char?buffer[256]?=?"RANDBWR?test!";?
???struct?fcb?blk;?
???int?result;?
???/*?get?new?file?name?from?user?*/?
???printf("Enter?a?file?name?to?create?(no?path?-?ie.?a:file.dat\n");?
???gets(line);?
???/*?parse?the?new?file?name?to?the?dta?*/?
???parsfnm(line,&blk,1);?
???printf("Drive?#%d??File:?%s\n",?blk.fcb_drive,?blk.fcb_name);?
???/*?request?DOS?services?to?create?file?*/?
???if?(bdosptr(0x16,?&blk,?0)?==?-1)?
???{?
??????perror("Error?creating?file");?
??????exit(1);?
???}?
???/*?save?old?dta?and?set?new?dta?*/?
???save_dta?=?getdta();?
???setdta(buffer);?
???/*?write?new?records?*/?
???blk.fcb_recsize?=?256;?
???blk.fcb_random?=?0L;?
???result?=?randbwr(&blk,?1);?
???if?(!result)?
??????printf("Write?OK\n");?
???else?
???{?
??????perror("Disk?error");?
??????exit(1);?
???}?
???/*?request?DOS?services?to?close?the?file?*/?
???if?(bdosptr(0x10,?&blk,?0)?==?-1)?
???{?
??????perror("Error?closing?file");?
??????exit(1);?
???}?
???/*?reset?the?old?dta?*/?
???setdta(save_dta);?
???return?0;?
}?
??
??
函数名:?random?
功??能:?随机数发生器?
用??法:?int?random(int?num);?
程序例:?
#include?<stdlib.h>?
#include?<stdio.h>?
#include?<time.h>?
/*?prints?a?random?number?in?the?range?0?to?99?*/?
int?main(void)?
{?
???randomize();?
???printf("Random?number?in?the?0-99?range:?%d\n",?random?(100));?
???return?0;?
}?
??
??
函数名:?randomize?
功??能:?初始化随机数发生器?
用??法:?void?randomize(void);?
程序例:?
#include?<stdlib.h>?
#include?<stdio.h>?
#include?<time.h>?
int?main(void)?
{?
???int?i;?
???randomize();?
???printf("Ten?random?numbers?from?0?to?99\n\n");?
???for(i=0;?i<10;?i++)?
???????printf("%d\n",?rand()?%?100);?
???return?0;?
}?
??
??
函数名:?read?
功??能:?从文件中读?
用??法:?int?read(int?handle,?void?*buf,?int?nbyte);?
程序例:?
#include?<stdio.h>?
#include?<io.h>?
#include?<alloc.h>?
#include?<fcntl.h>?
#include?<process.h>?
#include?<sys\stat.h>?
int?main(void)?
{?
???void?*buf;?
???int?handle,?bytes;?
???buf?=?malloc(10);?
/*?
???Looks?for?a?file?in?the?current?directory?named?TEST.$$$?and?attempts?
???to?read?10?bytes?from?it.??To?use?this?example?you?should?create?the?
???file?TEST.$$$?
*/?
???if?((handle?=?
??????open("TEST.$$$",?O_RDONLY?|?O_BINARY,?S_IWRITE?|?S_IREAD))?==?-1)?
???{?
??????printf("Error?Opening?File\n");?
??????exit(1);?
???}?
???if?((bytes?=?read(handle,?buf,?10))?==?-1)?{?
??????printf("Read?Failed.\n");?
??????exit(1);?
???}?
???else?{?
??????printf("Read:?%d?bytes?read.\n",?bytes);?
???}?
???return?0;?
}?
??
??
函数名:?realloc?
功??能:?重新分配主存?
用??法:?void?*realloc(void?*ptr,?unsigned?newsize);?
程序例:?
#include?<stdio.h>?
#include?<alloc.h>?
#include?<string.h>?
int?main(void)?
{?
???char?*str;?
???/*?allocate?memory?for?string?*/?
???str?=?malloc(10);?
???/*?copy?"Hello"?into?string?*/?
???strcpy(str,?"Hello");?
???printf("String?is?%s\n??Address?is?%p\n",?str,?str);?
???str?=?realloc(str,?20);?
???printf("String?is?%s\n??New?address?is?%p\n",?str,?str);?
???/*?free?memory?*/?
???free(str);?
???return?0;?
}?
??
??
函数名:?rectangle?
功??能:?画一个矩形?
用??法:?void?far?rectangle(int?left,?int?top,?int?right,?int?bottom);?
程序例:?
#include?<graphics.h>?
#include?<stdlib.h>?
#include?<stdio.h>?
#include?<conio.h>?
int?main(void)?
{?
???/*?request?auto?detection?*/?
???int?gdriver?=?DETECT,?gmode,?errorcode;?
???int?left,?top,?right,?bottom;?
???/*?initialize?graphics?and?local?variables?*/?
???initgraph(&gdriver,?&gmode,?"");?
???/*?read?result?of?initialization?*/?
???errorcode?=?graphresult();?
???if?(errorcode?!=?grOk)??/*?an?error?occurred?*/?
???{?
??????printf("Graphics?error:?%s\n",?grapherrormsg(errorcode));?
??????printf("Press?any?key?to?halt:");?
??????getch();?
??????exit(1);?/*?terminate?with?an?error?code?*/?
???}?
???left?=?getmaxx()?/?2?-?50;?
???top?=?getmaxy()?/?2?-?50;?
???right?=?getmaxx()?/?2?+?50;?
???bottom?=?getmaxy()?/?2?+?50;?
???/*?draw?a?rectangle?*/?
???rectangle(left,top,right,bottom);?
???/*?clean?up?*/?
???getch();?
???closegraph();?
???return?0;?
}?
??
??
函数名:?registerbgidriver?
功??能:?登录已连接进来的图形驱动程序代码?
用??法:?int?registerbgidriver(void(*driver)(void));?
程序例:?
#include?<graphics.h>?
#include?<stdlib.h>?
#include?<stdio.h>?
#include?<conio.h>?
int?main(void)?
{?
???/*?request?auto?detection?*/?
???int?gdriver?=?DETECT,?gmode,?errorcode;?
???/*?register?a?driver?that?was?added?into?graphics.lib?*/?
???errorcode?=?registerbgidriver(EGAVGA_driver);?
???/*?report?any?registration?errors?*/?
???if?(errorcode?<?0)?
???{?
??????printf("Graphics?error:?%s\n",?grapherrormsg(errorcode));?
??????printf("Press?any?key?to?halt:");?
??????getch();?
??????exit(1);?/*?terminate?with?an?error?code?*/?
???}?
???/*?initialize?graphics?and?local?variables?*/?
???initgraph(&gdriver,?&gmode,?"");?
???/*?read?result?of?initialization?*/?
???errorcode?=?graphresult();?
???if?(errorcode?!=?grOk)??/*?an?error?occurred?*/?
???{?
??????printf("Graphics?error:?%s\n",?grapherrormsg(errorcode));?
??????printf("Press?any?key?to?halt:");?
??????getch();?
??????exit(1);?/*?terminate?with?an?error?code?*/?
???}?
???/*?draw?a?line?*/?
???line(0,?0,?getmaxx(),?getmaxy());?
???/*?clean?up?*/?
???getch();?
???closegraph();?
???return?0;?
}?
??
??
函数名:?remove?
功??能:?删除一个文件?
用??法:?int?remove(char?*filename);?
程序例:?
#include?<stdio.h>?
int?main(void)?
{?
???char?file[80];?
???/*?prompt?for?file?name?to?delete?*/?
???printf("File?to?delete:?");?
???gets(file);?
???/*?delete?the?file?*/?
???if?(remove(file)?==?0)?
??????printf("Removed?%s.\n",file);?
???else?
??????perror("remove");?
???return?0;?
}?
??
??
函数名:?rename?
功??能:?重命名文件?
用??法:?int?rename(char?*oldname,?char?*newname);?
程序例:?
#include?<stdio.h>?
int?main(void)?
{?
???char?oldname[80],?newname[80];?
???/*?prompt?for?file?to?rename?and?new?name?*/?
???printf("File?to?rename:?");?
???gets(oldname);?
???printf("New?name:?");?
???gets(newname);?
???/*?Rename?the?file?*/?
???if?(rename(oldname,?newname)?==?0)?
??????printf("Renamed?%s?to?%s.\n",?oldname,?newname);?
???else?
??????perror("rename");?
???return?0;?
}?
??
??
函数名:?restorecrtmode?
功??能:?将屏幕模式恢复为先前的imitgraph设置?
用??法:?void?far?restorecrtmode(void);?
程序例:?
#include?<graphics.h>?
#include?<stdlib.h>?
#include?<stdio.h>?
#include?<conio.h>?
int?main(void)?
{?
???/*?request?auto?detection?*/?
???int?gdriver?=?DETECT,?gmode,?errorcode;?
???int?x,?y;?
???/*?initialize?graphics?and?local?variables?*/?
???initgraph(&gdriver,?&gmode,?"");?
???/*?read?result?of?initialization?*/?
???errorcode?=?graphresult();?
???if?(errorcode?!=?grOk)??/*?an?error?occurred?*/?
???{?
??????printf("Graphics?error:?%s\n",?grapherrormsg(errorcode));?
??????printf("Press?any?key?to?halt:");?
??????getch();?
??????exit(1);?/*?terminate?with?an?error?code?*/?
???}?
???x?=?getmaxx()?/?2;?
???y?=?getmaxy()?/?2;?
???/*?output?a?message?*/?
???settextjustify(CENTER_TEXT,?CENTER_TEXT);?
???outtextxy(x,?y,?"Press?any?key?to?exit?graphics:");?
???getch();?
???/*?restore?system?to?text?mode?*/?
???restorecrtmode();?
???printf("We‘re?now?in?text?mode.\n");?
???printf("Press?any?key?to?return?to?graphics?mode:");?
???getch();?
???/*?return?to?graphics?mode?*/?
???setgraphmode(getgraphmode());?
???/*?output?a?message?*/?
???settextjustify(CENTER_TEXT,?CENTER_TEXT);?
???outtextxy(x,?y,?"We‘re?back?in?graphics?mode.");?
???outtextxy(x,?y+textheight("W"),?"Press?any?key?to?halt:");?
???/*?clean?up?*/?
???getch();?
???closegraph();?
???return?0;?
}?
??
??
函数名:?rewind?
功??能:?将文件指针重新指向一个流的开头?
用??法:?int?rewind(FILE?*stream);?
程序例:?
#include?<stdio.h>?
#include?<dir.h>?
?int?main(void)?
?{?
????FILE?*fp;?
????char?*fname?=?"TXXXXXX",?*newname,?first;?
????newname?=?mktemp(fname);?
????fp?=?fopen(newname,"w+");?
????fprintf(fp,"abcdefghijklmnopqrstuvwxyz");?
????rewind(fp);?
????fscanf(fp,"%c",&first);?
????printf("The?first?character?is:?%c\n",first);?
????fclose(fp);?
????remove(newname);?
????return?0;?
}?
??
??
函数名:?rmdir?
功??能:?删除DOS文件目录?
用??法:?int?rmdir(char?*stream);?
程序例:?
#include?<stdio.h>?
#include?<conio.h>?
#include?<process.h>?
#include?<dir.h>?
#define?DIRNAME?"testdir.$$$"?
int?main(void)?
{?
???int?stat;?
???stat?=?mkdir(DIRNAME);?
???if?(!stat)?
??????????printf("Directory?created\n");?
???else?
???{?
??????printf("Unable?to?create?directory\n");?
??????exit(1);?
???}?
???getch();?
???system("dir/p");?
???getch();?
???stat?=?rmdir(DIRNAME);?
???if?(!stat)?
??????????printf("\nDirectory?deleted\n");?
???else?
???{?
???perror("\nUnable?to?delete?directory\n");?
??????exit(1);?
???}?
???return?0;?
}?
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