« Inline And Default arguments

Inline functions

Copy
1inline int max2(int a, int b)
2{
3    return a > b ? a : b;
4}
5
6int main()
7{
8    int a, b;
9    cin >> a >> b;
10
11    int c = (a > b) ? a : b;
12    c = max(a, b);
13}

Each time it will go to the function and return the value and then value is pushed to c. So a performance lag even though a very small one.

Copy
1int max(int a, int b)
2{
3    return a > b ? a : b;
4}
5
6int main()
7{
8    int a, b;
9    cin >> a >> b;
10
11    int c = (a > b) ? a : b;
12    c = max2(a, b);
13}

For inline function compiler will copy the function body at the place where its getting called. So we made our code readable plus there is no performance lag.

Why not make all functions inline?

So if we try to make all functions (big functions) inline then:

• a.out file will be bulkier as the program will be huge.
• When we write inline then we hint the compiler to please do it but its compiler's decision to do it or not
• If single line function compiler will do it, if 2-3 lines it might do or it might not, more than these number of lines it won't do

Default arguments

Copy
1int sum(int arr[], int size, int si = 0)
2{
3    int ans = 0;
4    for (int i = si; i < size; i++)
5    {
6        ans = ans + arr[i];
7    }
8    return ans;
9}

A Default value is given to si. All default variables should be at the rightmost places in the function call.

• function sum(normal, default, normal, default) This will not throw an error but it can create confusion to the function that you passed value to which argument.
• function sum(normal, normal, default, default) this is correct

Final code

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1#include <iostream>
2#include <iomanip>
3#include <algorithm>
4#include <string>
5#include <cstring>
6#include <vector>
7#include <cmath>
8#include <map>
9#include <climits>
10// climits for INT_MIN
11#include <unordered_map>
12using namespace std;
13
14int max(int a, int b)
15{
16    return a > b ? a : b;
17}
18
19inline int max2(int a, int b)
20{
21    return a > b ? a : b;
22}
23
24// default value given to si
25int sum(int arr[], int size, int si = 0)
26{
27    int ans = 0;
28    for (int i = si; i < size; i++)
29    {
30        ans = ans + arr[i];
31    }
32    return ans;
33}
34
35int sum2(int arr[], int size, int si = 0, int m)
36{
37    int ans = 0;
38    for (int i = si; i < size; i++)
39    {
40        ans = ans + arr[i];
41    }
42    return ans;
43}
44
45int main()
46{
47    int a, b;
48    cin >> a >> b;
49
50    int c = (a > b) ? a : b;
51    c = max(a, b);
52    c = max2(a, b);
53
54    int x, y;
55    cin >> x >> y;
56
57    int z = (x > y) ? x : y;
58    x = max(x, y);
59    x = max2(x, y);
60
61    int arr[20];
62    cout << sum(arr, 20, 0) << endl;
63    cout << sum(arr, 20) << endl;
64    // we can skip default values
65
66    cout << sum(arr, 20, 5) << endl;
67
68    cout << sum2(arr, 20, 5) << endl;
69
70    return 0;
71}