/*编写函数countpi，利用公式 计算π的近似值，当某一项的值小于10-5时，认为达到精度要求，请完善函数。将结果显示在屏幕上并输出到文件p7_3.out中。*/ #include<stdio.h> double countpi(double eps) /*eps为允许误差*/ { int m=1; double temp=1.0,s=0; while(temp>=eps) { s =temp; temp=temp*m/(2*m 1); m ; } return(2*s); } main() { FILE *fp; double eps=1e-5,pi; if((fp=fopen("p7_3.out","w"))==NULL) { printf("cannot open the file\n"); exit(0); } pi= countpi(eps); printf("pi=%lf\n",pi); fprintf(fp,"pi=%lf\n",pi); fclose(fp); system("pause"); }
