C + + Application two-dimensional array

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There is a two-dimensional array called New in the C + + programming language, which is more flexible to use, and there are several ways to help us implement certain functions. Here we will summarize several C + + two-dimensional array new application methods, to conduct a review.

C + + two-dimensional array new application method one:

1. A (*GA) [n] = new A[m][n];
2. ...
3. delete []ga;

Disadvantage: n must be a known

Advantages: Call intuitive, continuous storage, program concise (after testing, destructors can be called correctly)

C + + two-dimensional array new application method two:

1. a** ga = new a*[m];
2. for (int i = 0; I < m; i++)
3. Ga[i] = new A[n];
4. ...
5. for (int i = 0; I < m; i++)
6. delete []ga[i];
7. delete []ga;

Cons: Non-sequential storage, cumbersome procedures, GA for a** type

Pros: Call intuitive, n may not be known

C + + two-dimensional array new application method three:

1. * GA = new a[m*n];
2. ...
3. delete []ga;

Cons: Call not intuitive

Advantage: Continuous storage, n may not be known

C + + two-dimensional array new application Mode four:

1. Vector > ga;
2. Ga.resize (m); These three lines can be used
3. for (int i = 1; I < n; i++)//
4. Ga[i].resize (n); //
5. ...

Disadvantages: Non-continuous storage, debugging is not convenient, the compiler speed down, program expansion (actual speed difference is not small)

Advantages: Call intuitive, automatic destruction and free memory, you can call the STL-related functions, dynamic growth

C + + two-dimensional array new application Mode five:

1. Vector ga;
2. Ga.resize (M*n);

The combination of method 3,4

C + + two-dimensional array new application Method VI:

Improved version of 2

1. a** ga = new a*[m];
2. Ga[0] = new A[m*n];
3. for (int i = 1; I < m; i++)
4. Ga[i] = ga[i-1]+n;

C + + Application two-dimensional array