ch06 samples codes were modified

CPlusPlus20ForProgrammers-master/examples/ch06/fig06_03.cpp

@@ -1,35 +1,50 @@
 // fig06_03.cpp
 // Using range-based for.
-#include <format>
 #include <iostream>
 #include <array>
 
 int main() {
    std::array items{1, 2, 3, 4, 5}; // type inferred as array<int, 5>
 
+   std::array items2{1, 2, 3, 4, 5};
    // display items before modification
    std::cout << "items before modification: ";
    for (const int& item : items) { // item is a reference to a const int
-      std::cout << std::format("{} ", item); 
+      std::cout <<  item << "<-- items\n"; 
    }                       
+   std::cout << "items2 before modification:\n";
+   for (const int& item : items) { // item is a reference to a const int
+      std::cout <<  item << "<-- items2\n";
+   }
+
  
    // multiply the elements of items by 2
    for (int& item : items) { // item is a reference to an int
       item *= 2;
    }
 
-   // display items after modification
-   std::cout << "\nitems after modification: ";
-   for (const int& item : items) {
-      std::cout << std::format("{} ", item);
+   for (int item : items2) { // item is a reference to an int
+      item *= 2;
    }
 
+   // display items after modification
+   std::cout << "\nitems after modification: \n ";
+   for (const int& item : items) {
+      std::cout <<  item << "<-- items\n";
+   }
+
+   // display items after modification
+   std::cout << "\nitems2 after modification:\n ";
+   for (const int& item : items2) {
+      std::cout <<  item << "<-- items2\n";
+   }
+
+
    // sum elements of items using range-based for with initialization
    std::cout << "\n\ncalculating a running total of items' values:\n";
    for (int runningTotal{0}; const int& item : items) {
       runningTotal += item;
-      std::cout << std::format("item: {}; running total: {}\n",
-         item, runningTotal);
+      std::cout << " running total "<<  item << runningTotal<<"\n";
    }
 }
 

CPlusPlus20ForProgrammers-master/examples/ch06/fig06_04.cpp

@@ -1,6 +1,5 @@
 // fig06_04.cpp
 // Set array values to the even integers from 2 to 10.
-#include <fmt/format.h>
 #include <iostream>
 #include <array>
 
@@ -16,7 +15,7 @@ int main() {
 
    // output contents of array values in tabular format
    for (const int& value : values) {
-      std::cout << fmt::format("{}  ", value);
+      std::cout << value << "\n";
    }
 
    std::cout << '\n';

CPlusPlus20ForProgrammers-master/examples/ch06/fig06_05.cpp

@@ -13,7 +13,7 @@ int main() {
       total += item;
    }
 
-   std::cout << fmt::format("Total of array elements: {}\n", total);
+   std::cout << "Total of array elements: " << total);
 }
 
 

CPlusPlus20ForProgrammers-master/examples/ch06/fig06_06.cpp

@@ -13,11 +13,10 @@ int main() {
    for (int i{0}; const int& frequency : frequencies) {
       // output bar labels ("00-09:", ..., "90-99:", "100:")
       if (i < 10) {
-         std::cout << std::format("{:03d}-{:03d}: ",
-            i * 100, (i * 100) + 9);
+         std::cout << i * 100 << " " <<  (i * 100) + 9 << "\n";
       }
       else {
-         std::cout << std::format("{:>7d}: ", 100);
+         std::cout << 100 << "\n";
       }
 
       ++i;

CPlusPlus20ForProgrammers-master/examples/ch06/fig06_07.cpp

@@ -1,6 +1,6 @@
 // fig06_07.cpp
 // Die-rolling program using an array instead of switch.
-#include <format> // C++20: This will be #include <format>
+//#include <format> // C++20: This will be #include <format>
 #include <iostream>
 #include <array>
 #include <random>
@@ -9,7 +9,7 @@ int main() {
    // set up random-number generation
    std::random_device rd; // used to seed the default_random_engine
    std::default_random_engine engine{rd()}; // rd() produces a seed 
-   std::uniform_int_distribution randomDie{1, 6};
+   std::uniform_int_distribution randomDie{0, 6};
 
    constexpr size_t arraySize{7}; // ignore element zero
    std::array<int, arraySize> frequency{}; // initialize to 0s
@@ -19,11 +19,11 @@ int main() {
       ++frequency.at(randomDie(engine));
    }
 
-   std::cout << std::format("{}{:>13}\n", "Face", "Frequency");
+   std::cout <<  "Face " <<  " Frequency  \n";
 
    // output each array element's value
    for (size_t face{1}; face < frequency.size(); ++face) {
-      std::cout << std::format("{:>4}{:>13}\n", face, frequency.at(face));
+      std::cout << face << " " << frequency.at(face) << "\n";
    }
 }
 

CPlusPlus20ForProgrammers-master/examples/ch06/fig06_08.cpp

@@ -1,6 +1,6 @@
 // fig06_08.cpp
 // Poll analysis program.
-#include <format> // C++20: This will be #include <format>
+//#include <format> // C++20: This will be #include <format>
 #include <iostream>
 #include <array>
 
@@ -19,12 +19,11 @@ int main() {
       ++frequency[response];//.at(response);
    }
    
-   std::cout << std::format("{}{:>12}\n", "Rating", "Frequency");
+   std::cout << "Rating   Frequency  \n";
 
    // output each array element's value
    for (size_t rating{1}; rating < frequency.size(); ++rating) {
-      std::cout << std::format("{:>6}{:>12}\n",
-         rating, frequency.at(rating));
+      std::cout << rating << " " << frequency.at(rating) << "\n";
    }
 }
 

CPlusPlus20ForProgrammers-master/examples/ch06/fig06_11.cpp

@@ -1,14 +1,14 @@
 // fig06_11.cpp
 // Compute the sum of the elements of an array using accumulate.
 #include <array>
-#include <fmt/format.h>
 #include <iostream>
 #include <numeric>
 
 int main() {
    constexpr std::array integers{10, 20, 30, 40};
-   std::cout << fmt::format("Total of array elements: {}\n",
-      std::accumulate(std::begin(integers), std::end(integers), 0));
+   std::cout << "Total of array elements "<< std::accumulate(std::begin(integers), std::end(integers), 0) <<"\n";
+   std::cout << "Total of array elements "<< std::accumulate(integers.cbegin(), integers.cend(), 0) <<"\n";
+   std::cout << "1 to 2 of array elements "<< std::accumulate(&integers[1], &integers[3], 0) <<"\n";
 }
 
 /**************************************************************************

CPlusPlus20ForProgrammers-master/examples/ch06/fig06_12.cpp

@@ -1,24 +1,32 @@
 // fig06_12.cpp
 // Compute the product of an array's elements using accumulate.
 #include <array>
-#include <format>
 #include <iostream>
 #include <numeric>
 
-int multiply(int x, int y) {
+template <typename T>
+T multiply(T x, T y) {
    return x * y;
 }
 
+
+int multiply_int(int x, int y) {
+   return x * y;
+}
+
+
 int main() {
    constexpr std::array integers{1, 2, 3, 4, 5};
+   constexpr std::array floats {1.0, 2.0, 3.0, 4.0, 5.0};
    auto multiply_lambda = [](const auto& x, const auto& y) {return x * y; };
 
-   std::cout << std::format("Product of integers: {}\n", std::accumulate(
-      std::begin(integers), std::end(integers), 1, multiply));
+   std::cout << "Product of integers: " <<  std::accumulate( std::begin(integers), std::end(integers), 1, multiply<int>) << "\n";
 
-   std::cout << std::format("Product of integers with a lambda: {}\n",
-      std::accumulate(std::begin(integers), std::end(integers), 1,
-         multiply_lambda));
+   std::cout << "Product of integers with a lambda: " << std::accumulate(std::begin(integers), std::end(integers), 1, multiply_lambda) << "\n";
+
+   std::cout << "Product of integers with a lambda: " << std::accumulate(std::begin(floats), std::end(floats), 1, multiply_int) << "\n";
+
+   std::cout << "Product of integers with a lambda: " << std::accumulate(std::begin(floats), std::end(floats), 1, multiply_lambda) << "\n";
 }