average and standard deviation-平均数和标准差(4个数)，允许重复计算：
//averageandstandarddeviation-平均数和标准差#include<iostream>#include<cmath>usingnamespacestd;doubleaverage(doubles1,doubles2,doubles3,doubles4);doublestandard_deviation(doubles1,doubles2,doubles3,doubles4,doubleaverage);intmain(){doubles1,s2,s3,s4;doubleave,sta_dev;charans;do{cout<<"Pleaseinputfournumbers:\n";cin>>s1>>s2>>s3>>s4;ave=average(s1,s2,s3,s4);sta_dev=standard_deviation(s1,s2,s3,s4,ave);cout<<"Theaverageis"<<ave<<endl;cout<<"Thestandarddeviationis"<<sta_dev<<endl;cout<<"Doyouwantagain?";cin>>ans;}while('y'==ans||'Y'==ans);return0;}doubleaverage(doubles1,doubles2,doubles3,doubles4){return(s1+s2+s3+s4)/4;}doublestandard_deviation(doubles1,doubles2,doubles3,doubles4,doubleaverage){returnsqrt((pow((s1-average),2)+pow((s2-average),2)+pow((s3-average),2)+pow((s4-average),2))/4);}
结果：
Pleaseinputfournumbers:1234Theaverageis2.5Thestandarddeviationis1.11803Doyouwantagain?yPleaseinputfournumbers:12.313.410.59.0Theaverageis11.3Thestandarddeviationis1.68375Doyouwantagain?yPleaseinputfournumbers:5555Theaverageis5Thestandarddeviationis0Doyouwantagain?
