[英]How to read an argument in from command line into a double?
這個程序首先分叉然后由execlp運行,它的調用程序傳遞兩個數字,一個冪和一個基數。
int main(int argc, char *argv[])
{
int pid = getpid();
printf("Calculator Process[%d]: started\n",pid);
double base, power;
sscanf(argv[1],"%d",&base);
sscanf(argv[2],"%d",&power);
double number = pow(base,power);
printf("Calculator Process[%d]: %d ^^ %d == %d\n",pid,base,power,number);
printf("Calculator Process[%d]: exiting\n",pid);
return 1;
}
讓我們說我進入它的基礎3,力量5.這就是我得到的:
base = 4263 -- this also happens to be the PID. power = -1 raised to power: 714477568
通話線路:
execlp("./calculator","./calculator",argv[1],argv[2],(char*)0);
當我打印argvs時,我得到它們的值(作為char *,但是轉換失敗)。
任何想法為什么我不能正確讀入值?
閱讀雙倍:
double base, power;
sscanf(argv[1],"%lf",&base);
sscanf(argv[2],"%lf",&power);
或者掃描成整數:
int base, power;
sscanf(argv[1],"%d",&base);
sscanf(argv[2],"%d",&power);
快速調整代碼應該這樣做:
int main(int argc, char *argv[])
{
int pid = getpid();
printf("Calculator Process[%d]: started\n",pid);
double base, power;
base = atof(argv[1]);
power = atof(argv[2]);
double number = pow(base,power);
printf("Calculator Process[%d]: %f ^^ %f == %f\n",pid,base,power,number);
printf("Calculator Process[%d]: exiting\n",pid);
return 1;
}
atof()
%f
否則它們將無法在輸出中顯示!
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