//8.1編寫一個輸出字符串的函數,有一個默認參數表示輸出次數,默認為1.(原題太扯啦,題意基礎上小改動) #includeusing namespace std; void show (const char* str, int time=1) { unsigned n=(time>0)?time:-time; for (unsigned i = 0; i < n; ++i) cout << str << endl; cout << "-----------------" << endl; } int main () { const char* str = "hello word!"; show(str); show(str,0); show(str,1); show(str,-1); }
//8.2CandyBar結構體有品牌,重量和熱量3個成員,編寫一個含有默認值的函數為成員賦值和一個顯示內容函數 //CandyBar& candbar, const char* strBrand = "Millennium Munch", double weight = 2.85, int calories = 350 #includeusing namespace std; struct CandyBar { string Brand; double weight; int calories; }; void input (CandyBar& candbar, const char* Brand = "Millennium Munch", double weight = 2.85, int calories = 350) { candbar.Brand = Brand; candbar.weight = weight; candbar.calories = calories; } void show (const CandyBar& candbar) { cout << candbar.Brand << '\t' << candbar.weight << '\t' << candbar.calories << endl; } int main () { CandyBar candbar1, candbar2; input(candbar1); show(candbar1); input(candbar2, "world", 2,3 ); show(candbar2); }
//8.3編寫一個函數,接受string引用,並把string內容變大寫,之後利用循環測試 #include#include using namespace std; string& upper (string& str) { for (char& e : str) e = (char)toupper(e); return (str); } int main () { while (true) { cout << "Enter a string (q to quit): "; string str; getline(cin, str); if (!cin || "q" == str || "Q" == str) break; cout << upper(str) << endl; } }
//8.4按以下程序框架,完成函數 #include#include using namespace std; struct stringy { char * str; int ct; }; void set (stringy& stry, const char* szTxt) { stry.ct = (int)strlen(szTxt); stry.str = new char [stry.ct + 1]; strcpy(stry.str, szTxt); } void show (const char* szTxt, unsigned times = 1) { for (unsigned i = 0; i < times; ++i) cout << szTxt << endl; } void show (const stringy& stry, unsigned times = 1) { for (unsigned i = 0; i < times; ++i) cout << stry.str << endl; } void destroy (stringy& stry) { delete [] stry.str; stry.str = NULL; } int main() { stringy beany; char testing[] = "Reality isn't what it used to be."; set(beany, testing); show(beany); show(beany, 2); destroy(beany); testing[0] = 'D'; testing[1] = 'u'; show(testing); show(testing, 3); show("Done!"); }
//8.5利用一個模板函數max5(),返回給予的5個數的最大值(應用c++11的array) #include#include using namespace std; template const T& max5 (const array & arr) { unsigned max = 0; for (unsigned i = 0; i < 5; ++i) if (arr[i] > arr[max]) max = i; return (arr[max]); } int main () { array iarray = {32, 20, 99, 256, 9}; for (const auto& e : iarray) cout << e << ' '; cout << " max: " << max5(iarray) << endl; array darray = {1.2,2.3,4.5,32.3,4.3}; for (const auto& e : darray) cout << e << ' '; cout << "max: " << max5(darray) << endl; }
//8.6編寫模板函數maxn(),參數為一個數組和元素數目,返回數組最大值, //然後具體化一個字符串為元素的字符串,返回最長字符串 #include#include using namespace std; template const T& maxn (const T arr[], unsigned n) { unsigned max = 0; for (unsigned i = 0; i < n; ++i) if (arr[i] > arr[max]) max = i; return (arr[max]); } char* maxn ( char* arr[], unsigned n) { unsigned max = 0; for (unsigned i = 0; i < n; ++i) if (strlen(arr[i]) > strlen(arr[max])) max = i; return (arr[max]); } int main () { int iArray[] = {32, -1, 99, 0, 256, 9}; for (const auto& e : iArray) cout << e << ' '; cout << " ----max: " << maxn(iArray, sizeof(iArray)/sizeof(iArray[0])) << endl; double dArray[] = {-3.2, 221.22, 9.9, 0, 1}; for (const auto& e : dArray) cout << e << ' '; cout << " ----max: " << maxn(dArray, sizeof(dArray)/sizeof(dArray[0])) << endl; const char* szArray[] = {"aaaa","bbbbbb","cc","fffffffffff","kkkk"}; for (const auto& e : szArray) cout << '\"' << e << '\"' << ' '; cout << " ----max: " << '\"' << maxn(szArray, sizeof(szArray)/sizeof(szArray[0])) << '\"' << endl; }
//8.7對程序清單8.14,使用兩個SumArray()模板返回數組元素總和。程序返回thing以及debt的總和 #includeusing namespace std; struct debts { char name[50]; double amount; }; template double SumArray(T arr[], int n) { cout << "template A\n"; double sum = 0; for (int i = 0; i < n; i++) sum += arr[i]; return (sum); } template double SumArray(T * arr[], int n) { cout << "template B\n"; double sum = 0; for (int i = 0; i < n; i++) sum += *arr[i]; return (sum); } int main() { int things[6] = {13, 31, 103, 301, 310, 130}; struct debts mr_E[3] = { {"Ima Wolfe", 2400.0},{"Ura Foxe", 1300.0},{"Iby Stout", 1800.0} }; double * pd[3]; for (int i = 0; i < 3; i++) pd[i] = &mr_E[i].amount; cout << "the total number of Mr. E's things: " << SumArray(things, 6) << endl; cout << "the sum of Mr. E's all debts: " << SumArray(pd, 3) << endl; }