C 语言库函数

函数名: sbrk 功 能: 改变数据段空间位置 用 法: char *sbrk(int incr); 程序例: #include <stdio.h> #include <alloc.h> int main(void) { printf("Changing allocation with sbrk()\n"); printf("Before sbrk() call: %lu bytes free\n", (unsigned long) coreleft()); sbrk(1000); printf(" After sbrk() call: %lu bytes free\n", (unsigned long) coreleft()); return 0; } 函数名: scanf 功 能: 执行格式化输入 用 法: int scanf(char *format[,argument,...]); 程序例: #include <stdio.h> #include <conio.h> int main(void) { char label[20]; char name[20]; int entries = 0; int loop, age; double salary; struct Entry_struct { char name[20]; int age; float salary; } entry[20]; /* Input a label as a string of characters restricting to 20 characters */ printf("\n\nPlease enter a label for the chart: "); scanf("%20s", label); fflush(stdin); /* flush the input stream in case of bad input */ /* Input number of entries as an integer */ printf("How many entries will there be? (less than 20) "); scanf("%d", &entries); fflush(stdin); /* flush the input stream in case of bad input */ /* input a name restricting input to only letters upper or lower case */ for (loop=0;loop<entries;++loop) { printf("Entry %d\n", loop); printf(" Name : "); scanf("%[A-Za-z]", entry[loop].name); fflush(stdin); /* flush the input stream in case of bad input */ /* input an age as an integer */ printf(" Age : "); scanf("%d", &entry[loop].age); fflush(stdin); /* flush the input stream in case of bad input */ /* input a salary as a float */ printf(" Salary : "); scanf("%f", &entry[loop].salary); fflush(stdin); /* flush the input stream in case of bad input */ } /* Input a name, age and salary as a string, integer, and double */ printf("\nPlease enter your name, age and salary\n"); scanf("%20s %d %lf", name, &age, &salary); /* Print out the data that was input */ printf("\n\nTable %s\n",label); printf("Compiled by %s age %d $%15.2lf\n", name, age, salary); printf("-----------------------------------------------------\n"); for (loop=0;loop<entries;++loop) printf("%4d | %-20s | %5d | %15.2lf\n", loop + 1, entry[loop].name, entry[loop].age, entry[loop].salary); printf("-----------------------------------------------------\n"); return 0; } 函数名: searchpath 功 能: 搜索DOS路径 用 法: char *searchpath(char *filename); 程序例: #include <stdio.h> #include <dir.h> int main(void) { char *p; /* Looks for TLINK and returns a pointer to the path */ p = searchpath("TLINK.EXE"); printf("Search for TLINK.EXE : %s\n", p); /* Looks for non-existent file */ p = searchpath("NOTEXIST.FIL"); printf("Search for NOTEXIST.FIL : %s\n", p); return 0; } 函数名: sector 功 能: 画并填充椭圆扇区 用 法: void far sector(int x, int y, int stangle, int endangle); 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 midx, midy, i; int stangle = 45, endangle = 135; int xrad = 100, yrad = 50; /* 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 */ } midx = getmaxx() / 2; midy = getmaxy() / 2; /* loop through the fill patterns */ for (i=EMPTY_FILL; i<USER_FILL; i++) { /* set the fill style */ setfillstyle(i, getmaxcolor()); /* draw the sector slice */ sector(midx, midy, stangle, endangle, xrad, yrad); getch(); } /* clean up */ closegraph(); return 0; } 函数名: segread 功 能: 读段寄存器值 用 法: void segread(struct SREGS *segtbl); 程序例: #include <stdio.h> #include <dos.h> int main(void) { struct SREGS segs; segread(&segs); printf("Current segment register settings\n\n"); printf("CS: %X DS: %X\n", segs.cs, segs.ds); printf("ES: %X SS: %X\n", segs.es, segs.ss); return 0; } 函数名: setactivepage 功 能: 设置图形输出活动页 用 法: void far setactivepage(int pagenum); 程序例: #include <graphics.h> #include <stdlib.h> #include <stdio.h> #include <conio.h> int main(void) { /* select a driver and mode that supports */ /* multiple pages. */ int gdriver = EGA, gmode = EGAHI, errorcode; int x, y, ht; /* 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; ht = textheight("W"); /* select the off screen page for drawing */ setactivepage(1); /* draw a line on page #1 */ line(0, 0, getmaxx(), getmaxy()); /* output a message on page #1 */ settextjustify(CENTER_TEXT, CENTER_TEXT); outtextxy(x, y, "This is page #1:"); outtextxy(x, y+ht, "Press any key to halt:"); /* select drawing to page #0 */ setactivepage(0); /* output a message on page #0 */ outtextxy(x, y, "This is page #0."); outtextxy(x, y+ht, "Press any key to view page #1:"); getch(); /* select page #1 as the visible page */ setvisualpage(1); /* clean up */ getch(); closegraph(); return 0; } 函数名: setallpallette 功 能: 按指定方式改变所有的调色板颜色 用 法: void far setallpallette(struct palette, far *pallette); 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; struct palettetype pal; int color, maxcolor, ht; int y = 10; char msg[80]; /* 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 */ } maxcolor = getmaxcolor(); ht = 2 * textheight("W"); /* grab a copy of the palette */ getpalette(&pal); /* display the default palette colors */ for (color=1; color<=maxcolor; color++) { setcolor(color); sprintf(msg, "Color: %d", color); outtextxy(1, y, msg); y += ht; } /* wait for a key */ getch(); /* black out the colors one by one */ for (color=1; color<=maxcolor; color++) { setpalette(color, BLACK); getch(); } /* restore the palette colors