C语言版计算器代码请求注释

我的选修课是制作c语言版的计算器，我下载的代码 ，可以执行，但有很多语句不知道是什么意思，特请求各位朋友帮忙，为代码添加注释，以便于我写设计文档，非常感谢！我的邮箱是guohaocun.2008@yahoo.com.cn或者guohaocun.2008@163.com. 以下是我的代码：

#include <stdlib.h>
#include <math.h>
#include <graphics.h>
#include <stdio.h>
#include <process.h>
#define EXCAPE 27
#define ENTER 13
main(){
int press,i,x,y,x1,y1,ch_z=0;
int dian=0;
char ch=’0′; /*input + – * / */
char emp[80],sum[80],*e,*s;
double yuan=0.000000000000;
void init(void);
void clear_z(char *u);
double strtoflt(char *p);
int getkey();
int gd=DETECT, gm;
initgraph(&gd, &gm, “”);
e=emp;
s=sum;
init();
x = (getmaxx() / 2) – 120;
y = (getmaxy() / 2) – 150;
x1 = (getmaxx() / 2) + 120;
y1 = (getmaxy() / 2) + 150;
while(1){
press = getkey();
switch(press){
case EXCAPE:
exit(0);
case 47:
bar (x + 10, y + 80 + 10, x + 60 – 10, y + 80 + 60 – 10);
delay(8000);
init();
if (ch!=’0′){
switch(ch){
case ‘/’:
if (strtoflt(emp)==0.0){
ch=’0′;
ch_z=0;
dian=0;
emp[0]=’\0′;
sum[0]=’\0′;
e=emp;
s=sum;
outtextxy(x+30,y+40,”error!!!!!”);
break;
}
yuan = strtoflt(sum) / strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
break;
case ‘*’:
yuan = strtoflt(sum) * strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
break;
case ‘+’:
yuan = strtoflt(sum) + strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
break;
case ‘-’:
if (strtoflt(sum)>=strtoflt(emp)){
yuan = strtoflt(sum) – strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
}
else{
yuan=strtoflt(emp)-strtoflt(sum);
sprintf(sum,”-%0.10f”,yuan);
}
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
}
}
else{
if (ch_z==0){
outtextxy(x+30,y+40,emp);
stpcpy(sum,emp);

}
else{
outtextxy(x+30,y+40,sum);

}
}
ch=’/';
ch_z=0;
emp[0]=’\0′;
e=emp;
dian=0;
break;
case 42:
bar (x + 60 + 10, y + 80 + 10, x + 60 * 2 – 10, y + 80 + 60 – 10);
delay(8000);
init();
if (ch!=’0′){
switch(ch){
case ‘/’:
yuan = strtoflt(sum) / strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘*’:
yuan = strtoflt(sum) * strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘+’:
yuan = strtoflt(sum) + strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘-’:
if (strtoflt(sum)>=strtoflt(emp)){
yuan = strtoflt(sum) – strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
}
else{
yuan=strtoflt(emp)-strtoflt(sum);
sprintf(sum,”-%0.10f”,yuan);
}
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
}
}
else{
if (ch_z==0){
outtextxy(x+30,y+40,emp);
stpcpy(sum,emp);
e=emp;
}
else
outtextxy(x+30,y+40,sum);
}
ch=’*';
ch_z=0;
dian=0;
break;
case 45:
bar (x + 60 * 2 + 10, y + 80 + 10, x + 60 * 3 – 10, y + 80 + 60 – 10);
delay(8000);
init();
if (ch!=’0′){
switch(ch){
case ‘/’:
yuan = strtoflt(sum) / strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘*’:
yuan = strtoflt(sum) * strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘+’:
yuan = strtoflt(sum) + strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘-’:
if (strtoflt(sum)>=strtoflt(emp)){
yuan = strtoflt(sum) – strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
}
else{
yuan=strtoflt(emp)-strtoflt(sum);
sprintf(sum,”-%0.10f”,yuan);
}
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
}
}
else{
if (ch_z==0){
outtextxy(x+30,y+40,emp);
stpcpy(sum,emp);
e=emp;
}
else
outtextxy(x+30,y+40,sum);
}
ch=’-';
ch_z=0;
dian=0;
break;
case 43:
bar (x + 60 * 3 + 10, y + 80 + 10, x + 60 * 4 – 10, y + 80 + 60 – 10);
delay(8000);
init();
if (ch!=’0′){
switch(ch){
case ‘/’:
yuan = strtoflt(sum) / strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘*’:
yuan = strtoflt(sum) * strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘+’:
yuan = strtoflt(sum) + strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘-’:
if (strtoflt(sum)>=strtoflt(emp)){
yuan = strtoflt(sum) – strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
}
else{
yuan=strtoflt(emp)-strtoflt(sum);
sprintf(sum,”-%0.10f”,yuan);
}
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
}
}
else{
if (ch_z==0){
outtextxy(x+30,y+40,emp);
stpcpy(sum,emp);
e=emp;
}
else
outtextxy(x+30,y+40,sum);
}
ch=’+';
ch_z=0;
dian=0;
break;
case 49:
bar (x + 10, y + 80 + 53 + 10, x + 60 – 10, y + 80 + 53 * 2 – 4);
delay(8000);
init();
for (i=0;i<=79;i++){
if (emp[i]==’\0′)
break;
}
if (ch_z==0){
*e=’1′;e++;*e=’\0′;
outtextxy(x+30,y+40,emp);
}
else{
outtextxy(x+30,y+40,sum);
}
break;
case 50:
bar (x + 60 + 10, y + 80 + 53 + 10, x + 60 * 2 – 10, y + 80 + 53 * 2 – 4);
delay(8000);
init();
for (i=0;i<=79;i++){
if (emp[i]==’\0′)
break;
}
if (ch_z==0){
*e=’2′;e++;*e=’\0′;
outtextxy(x+30,y+40,emp);
}
else{
outtextxy(x+30,y+40,sum);
}
break;
case 51:
bar (x + 60 * 2 + 10, y + 80 + 53 + 10, x + 60 * 3 – 10, y + 80 + 53 * 2 – 4);
delay(8000);
init();
for (i=0;i<=79;i++){
if (emp[i]==’\0′)
break;
}
if (ch_z==0){
*e=’3′;e++;*e=’\0′;
outtextxy(x+30,y+40,emp);
}
else{
outtextxy(x+30,y+40,sum);
}
break;
case ENTER:
bar (x + 60 * 3 + 10, y + 80 + 53 + 10, x + 60 * 4 – 10, y + 80 + 53 * 2 – 4);
delay(8000);
init();
if (ch!=’0′){
switch(ch){
case ‘/’:
yuan = strtoflt(sum) / strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘*’:
yuan = strtoflt(sum) * strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘+’:
yuan = strtoflt(sum) + strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
case ‘-’:
if (strtoflt(sum)>=strtoflt(emp)){
yuan = strtoflt(sum) – strtoflt(emp);
sprintf(sum,”%0.10f”,yuan);
}
else{
yuan=strtoflt(emp)-strtoflt(sum);
sprintf(sum,”-%0.10f”,yuan);
}
clear_z(sum);
outtextxy(x+30,y+40,sum);
emp[0]=’\0′;
e=emp;
break;
}
}
else{
if (ch_z==0){
outtextxy(x+30,y+40,emp);
stpcpy(sum,emp);
e=emp;
}
else{
outtextxy(x+30,y+40,sum);
}
}
ch=’0′;
ch_z=1;
dian=0;
break;
case 52:
bar (x + 10, y + 80 + 53 * 2 + 10, x + 60 – 10, y + 80 + 53 * 3 – 4);
delay(8000);
init();
if (ch_z==0){
*e=’4′;e++;*e=’\0′;
outtextxy(x+30,y+40,emp);
}
else{
outtextxy(x+30,y+40,sum);
}
break;
case 53:
bar (x + 60 + 10, y + 80 + 53 * 2 + 10, x + 60 * 2 – 10, y + 80 + 53 * 3 – 4);
delay(8000);
init();
if (ch_z==0){
*e=’5′;e++;*e=’\0′;
outtextxy(x+30,y+40,emp);
}
else{
outtextxy(x+30,y+40,sum);
}
break;
case 54:
bar (x + 60 * 2 +10, y + 80 + 53 * 2 + 10, x + 60 * 3 – 10, y + 80 + 53 * 3 – 4);
delay(8000);
init();
if (ch_z==0){
*e=’6′;e++;*e=’\0′;
outtextxy(x+30,y+40,emp);
}
else{
outtextxy(x+30,y+40,sum);
}
break;
case 46:
bar (x + 60 * 3 + 10, y + 80 + 53 * 2 + 10, x + 60 * 4 – 10, y + 80 + 53 * 3 – 4);
delay(8000);
init();
if (dian==0){
if (ch_z==0){
*e=’.';e++;*e=’\0′;
outtextxy(x+30,y+40,emp);
}
else{
outtextxy(x+30,y+40,sum);
}
}
else{
if (ch_z==0)
outtextxy(x+30,y+40,emp);
else
outtextxy(x+30,y+40,sum);
}
dian=1;
break;
case 55:
bar (x + 10, y + 80 + 53 * 3 + 10, x + 60 – 10, y + 80 + 53 * 4 – 4);
delay(8000);
init();
if (ch_z==0){
*e=’7′;e++;*e=’\0′;
outtextxy(x+30,y+40,emp);
}
else{
outtextxy(x+30,y+40,sum);
}
break;
case 56:
bar (x + 60 + 10, y + 80 + 53 * 3 + 10, x + 60 * 2 -10, y + 80 + 53 * 4 – 4);
delay(8000);
init();
if (ch_z==0){
*e=’8′;e++;*e=’\0′;
outtextxy(x+30,y+40,emp);
}
else{
outtextxy(x+30,y+40,sum);
}
break;
case 57:
bar (x + 60 * 2 + 10, y + 80 + 53 * 3 + 10, x + 60 * 3 – 10, y + 80 + 53 * 4 – 4);
delay(8000);
init();
if (ch_z==0){
*e=’9′;e++;*e=’\0′;
outtextxy(x+30,y+40,emp);
}
else{
outtextxy(x+30,y+40,sum);
}
break;
case 48:
bar (x + 60 * 3 + 10, y + 80 + 53 * 3 + 10, x + 60 * 4 – 10, y + 80 + 53 * 4 – 4);
delay(8000);
init();
if (ch_z==0){
*e=’0′;e++;*e=’\0′;
outtextxy(x+30,y+40,emp);
}
else{
outtextxy(x+30,y+40,sum);
}
break;
case 32:
emp[0]=’\0′;
sum[0]=’\0′;
e=emp;
s=sum;
ch=’0′;
ch_z=0;
dian=0;
init();
break;
case 8:
delay(8000);
for(i=0;i<=79;i++){
if (emp[i]==’\0′)
break;
}
if (i==0)
break;
if (i!=79&&i!=0){
i–;
emp[i]=’\0′;
e=&emp[i];
}
init();
outtextxy(x+30,y+40,emp);
break;
}
}
}
/*———————————————————————*/
void init(void){
int x, y, x1, y1, i, j;
char emp;
x = (getmaxx() / 2) – 120;
y = (getmaxy() / 2) – 150;
x1 = (getmaxx() / 2) + 120;
y1 = (getmaxy() / 2) + 150;
cleardevice();
setbkcolor(5);
setfillstyle(1, 15);
setcolor(15);
settextstyle(1,0,1);
rectangle (x, y, x1, y1);
rectangle (x – 7, y – 7, x1 + 7, y1 + 7);
rectangle (x + 10, y + 10, x1 – 10, y + 80 – 10);
line (x, y + 80, x1, y + 80);
y = y + 80;
for (j = 1; j <= 4; j++){
x = (getmaxx() / 2) – 120;
for (i = 1; i <= 4; i++){
/* bar (x + 10, y + 10, x + 60 – 10, y + 60 – 10);*/
rectangle(x + 10, y + 10, x + 60 – 10, y + 60 – 10);
if (j == 1){
if (i == 1)
outtextxy(x + 20, y + 20, “/”);
if (i == 2)
outtextxy(x + 25, y + 20, “*”);
if (i == 3)
outtextxy(x + 27, y + 20, “-”);
if (i == 4)
outtextxy(x + 25, y + 20, “+”);
}
if (j == 2){
if (i == 1)
outtextxy(x + 25, y + 20, “1″);
if (i == 2)
outtextxy(x + 25, y + 20, “2″);
if (i == 3)
outtextxy(x + 25, y + 20, “3″);
if (i == 4)
outtextxy(x + 25, y + 20, “=”);
}
if (j == 3){
if (i == 1)
outtextxy(x + 25, y + 20, “4″);
if (i == 2)
outtextxy(x + 25, y + 20, “5″);
if (i == 3)
outtextxy(x + 25, y + 20, “6″);
if (i == 4)
outtextxy(x + 25, y + 20, “.”);
}
if (j == 4){
if (i == 1)
outtextxy(x + 25, y + 20, “7″);
if (i == 2)
outtextxy(x + 25, y + 20, “8″);
if (i == 3)
outtextxy(x + 25, y + 20, “9″);
if (i == 4)
outtextxy(x + 25, y + 20, “0″);
}
x = x + 60;
}
y = y + 53;
}
}
/*———————————————————————*/
int getkey(){
char lowbyte;
int press;
while(bioskey(1)==0);
press = bioskey(0);
press = press&0xff? press&0xff: press>>8;

return(press);

}
double strtoflt(char *p)
{
double rtl=0.000000000000;
double pnt=0.000000000000;
double t = 10;
int ispoint = 0;
while (*p!=’\0′||*p!=’.'){
if(*p<’0′||*p>’9′)
break;
rtl*=10;
rtl+=*p-’0′;
p++;
}
if (*p==’.'){
ispoint=1;
p++;
}
while(ispoint&&*p!=’\0′){
pnt+=(double)(*p-’0′)/t;
t*=10;
p++;
}
rtl+=pnt;
return (rtl);
}
/*———————————————————————–*/
void clear_z(char u[]){
int i;
for(i=strlen(u)-1;i>=0;i–){
if (u[i]!=’0′)
break;
}
if (u[i]==’.'){
u[i]=’\0′;
}
else{
i++;
u[i]=’\0′;
}
}