1 Fully parenthesize the following expressions:

    a = b + c ∗ d << 2 & 8
    a & 077 != 3
    a == b || a == c && c < 5
    c = x != 0
    0 <= i < 7
    f(1,2)+3
    a = − 1 + + b −− − 5
    a = b == c ++
    a = b = c = 0
    a[4][2] ∗= ∗ b ? c : ∗ d ∗ 2
    a−b,c=d

a = ((b + (c * d)) << 2) & 8;
(a & 077) != 3;
(a == b) || ((a == c) && (c < 5));
c = (x != 0);
(0 <= i) < 7;
f(1, 2) + 3;
a = (-1 ++)(b--) - 5; //complie error
a = (b == (c++));
a = (b = (c = 0));
a[4][2] *= (*b ? c : (*d * 2));
(a - b), (c = d);//逗号运算符

2 Read a sequence of possibly whitespace-separated (name,value) pairs, where the name is a single whitespace-separated word and the value is an integer or a floating-point value. Compute and print the sum and mean for each name and the sum and mean for all names. Hint: §10.2.8.

#include <iostream>
#include <map>
#include <string>
#include <vector>
#include <numeric>

using namespace std;

void solotion(map<string, vector<float>>& m)
{
	string s{};
	float f{};
	while (cin >> s >> f)
		m[s].push_back(f);
	cout.width(10); cout << left << "name";
	cout.width(10); cout << left << "sum";
	cout.width(10); cout << left << "mean" << endl;
	for (auto p : m)
	{
		cout.width(10); cout << left << p.first;
		float sum = std::accumulate(p.second.begin(), p.second.end(), 0);
		cout.width(10); cout << left << sum;
		float mean = sum / p.second.size();
		cout.width(10); cout << left << mean << endl;
	}
}

int main()
{
	map<string, vector<float>> msf{};
	solotion(msf);
	return 0;
}

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [22:16:31] 
$ g++ 11-2.cpp -std=c++11 

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [22:17:02] 
$ ./a.out
zxc 1
zxc 2
zxc 3
asd 4
qwe 6
qwe 8
name      sum       mean      
asd       4         4         
qwe       14        7         
zxc       6         2

3 Write a table of values for the bitwise logical operations (§11.1.1) for all possible combinations of 0 and 1 operands.

`&`	0	1
0	0	0
1	0	1

|||0|1| |:---:|:---:|:---:| |0|0|1| |1|1|1|

`^`	0	1
0	0	1
1	1	0

4 Write 5 expressions for which the order of evaluation is undefined. Execute them to see what one or – preferably – more implementations do with them.

#include <iostream>
#include <map>
#include <string>
#include <vector>

using namespace std;

int f(const int a)
{
	cout << "f(int) is running" << endl;
	return a;
}

int g(int a)
{
	cout << "g(int) is running" << endl;
	return a;
}

int f1(int a,int b )
{
	cout << "in f1(int a,int b) a is " << a << " b is " << b << endl;
	return a;
}

int main()
{
	cout << "expression 1" << endl;
	int x = f(2) + g(3);


	int i = 2;
	int a[10]{  };
	cout << endl << "expression 2" << endl;
	a[i] = i++;
	cout << "i is " << i << endl;
	for (auto j : a)
		cout << j << " ";
	cout << endl;


	cout << endl << "expression 3" << endl;
	i = 3;
	f1(a[i], i++);

    //and so on
	return 0;
}

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [22:48:31] 
$ g++ 11-4.cpp -std=c++11

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [22:48:34] 
$ ./a.out 
expression 1
f(int) is running
g(int) is running

expression 2
i is 3
0 0 0 2 0 0 0 0 0 0 

expression 3
in f1(int a,int b) a is 0 b is 3

5 What happens if you divide by zero on your system? What happens in case of overflow and underflow?

#include <iostream>
#include <map>
#include <string>
#include <vector>

using namespace std;

int main()
{

	int a = -100000000000000000000000;
	int b = 1000000000000000000000000;
	int c = 0;
	cout << 5 / c << endl;
	return 0;
}

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [22:48:36] 
$ g++ 11-5.cpp -std=c++11
11-5.cpp:12:11: 警告：整数常量值超出其类型 [默认启用]
  int a = -100000000000000000000000;
           ^
11-5.cpp:13:10: 警告：整数常量值超出其类型 [默认启用]
  int b = 1000000000000000000000000;
          ^
11-5.cpp: 在函数‘int main()’中:
11-5.cpp:12:11: 警告：隐式常量转换溢出 [-Woverflow]
  int a = -100000000000000000000000;
           ^
11-5.cpp:13:10: 警告：隐式常量转换溢出 [-Woverflow]
  int b = 1000000000000000000000000;
          ^

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [22:51:56] 
$ ./a.out 
[1]    2796 floating point exception  ./a.out

6 Fully parenthesize(括号) the following expressions:

    ∗p++
    ∗−−p
    ++a−−
    (int∗)p−>m
    ∗p.m
    ∗a[i]

	*(p++);
	*(--p);
	++(a--);
	((int*)p)->m;
	(*p).m;
	*(a[i]);

7 Implement and test these functions: strlen() , which returns the length of a C-style string; strcpy() , which copies a C-style string into another; and strcmp() , which compares two C-style strings. Consider what the argument types and return types ought to be. Then compare your functions with the standard library versions as declared in ( <string.h> ) and as specified in §43.4.

unsigned int strlen(const char * p)
{
	int i = 0;
	while (*(p + i) != '\0')
		i++;
	return i;
}

void strcpy(char *dest, const char* from)
{
	int i = 0;
	while (*(from + i) != '\0')
	{
		dest[i] = from[i];
		i++;
	}
}

bool strcmp(const char* a,const char* b)
//0 means a bigger,1 means b bigger
{
	int i = 0;
	while (*(a+i)!='\0'&& *(b+i)!='\0')
	{
		if (*(a + i) > *(b + i))
			return 0;
		else if (*(a + i) < *(b + i))
			return 1;
		i++;
	}
}

8 Modify the program from §X.11[2] to also compute the median.

#include <iostream>
#include <map>
#include <string>
#include <vector>
#include <numeric>

using namespace std;

void solotion(map<string, vector<float>>& m)
{
	string s{};
	float f{};
	while (cin >> s >> f)
		m[s].push_back(f);
	cout.width(10); cout << left << "name";
	cout.width(10); cout << left << "sum";
	cout.width(10); cout << left << "mean";
	cout.width(10); cout << left << "median" << endl;
	for (auto p : m)
	{
		cout.width(10); cout << left << p.first;
		float sum = std::accumulate(p.second.begin(), p.second.end(), 0);
		cout.width(10); cout << left << sum;
		float mean = sum / p.second.size();
		cout.width(10); cout << left << mean;
		cout.width(10); cout << left << p.second[p.second.size()/2] << endl;
	}
}

int main()
{
	map<string, vector<float>> msf{};
	solotion(msf);
	return 0;
}

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [0:37:29] 
$ g++ 11-8.cpp -std=c++11

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [0:38:34] 
$ ./a.out                
zxc 1               
zxc 2
zxc 3
zxc 4
asd 5
qwe 6
qwe 8
zxc 5
name      sum       mean      median    
asd       5         5         5         
qwe       14        7         8         
zxc       15        3         3

9 Write a function cat() that takes two C-style string arguments and returns a string that is the concatenation of the arguments. Use new to find store for the result.

#include <iostream>
#include <string>
using namespace std;

string* cat(const char *a, const char *b)
{
	string as = string(a);
	string bs = string(b);
	return new string(as + bs);
}

int main()
{
	const char *a = { "qwerty" };
	const char *b = { "zxcvbn" };
	auto s = cat(a, b);
	cout << *s << endl;
	return 0;
}

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [2:40:01] C:1
$ g++ 11-9.cpp -std=c++11

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [2:40:03] 
$ g++ 11-9.cpp -std=c++11

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [2:40:04] 
$ ./a.out 
qwertyzxcvbn

10 Write a function rev() that takes a C-style string argument and reverses the characters in it. That is, after rev(p) the last character of p will be the first, etc.

#include <iostream>
#include <string>
using namespace std;

void rev(char *a)
{
	int n = strlen(a);
	for (auto i = 0; i < n/2; i++)
		swap(*(a+i), *(a + n-i-1));

}

int main()
{
	char a[10] = {  };
	cin >> a;
	rev(a);
	for (auto i :a)
		cout << i;
	return 0;
}

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [3:02:07] 
$ g++ 11-10.cpp -std=c++11

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [3:02:08] 
$ ./a.out 
123456
654321

11 Type in the calculator example and get it to work. Do not ‘‘save time’’ by using an already entered text. You’ll learn most from finding and correcting ‘‘little silly errors.’’

//code in 11-11.cpp
// there is still some bug i can't find

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [3:02:13] 
$ g++ 11-11.cpp -std=c++11

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [3:21:06] 
$ ./a.out 
5+6
11
6*9
54
6-1
5
4/2
2

12 Modify the calculator to report line numbers for errors.

//i can't do this

13 Allow a user to define functions in the calculator. Hint: Define a function as a sequence of operations just as a user would have typed them. Such a sequence can be stored either as a character string or as a list of tokens. Then read and execute those operations when the function is called. If you want a user-defined function to take arguments, you will have to invent a notation for that.

//i can't do this

14 Convert the desk calculator to use a symbol structure instead of using the static variables number_value and string_value .

//i can't do this

15 Copy all even non-zero elements of an int[] into a vector . Use a pointer and ++ for the traversal.

i think this question may be X.12 1

#include <iostream>
#include <vector>
using namespace std;

int main()
{
	int a[]{ 0,1,0,2,0,3,0,4,0,5 };
	vector<int> v;
	for (auto i : a)
		if (i != 0)
			v.push_back(i);
	for (auto i : v)
		cout << i << endl;
	return 0;
}

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [3:37:52] 
$ g++ 11-15.cpp -std=c++11

# gaolex @ cv in ~/TCPPPL-4th-Exercises/X.11 on git:master x [3:37:55] 
$ ./a.out                 
1
2
3
4
5

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