标签：style http color io os ar for strong sp
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; }
标签：style http color io os ar for strong sp
原文地址：http://blog.csdn.net/shuilan0066/article/details/40295659
