C-language dynamic array implementation

I. Overview

The C language cannot directly define a dynamic array, and the array must determine the length at initialization time.

If you want to determine the length of the array while the program is running, you need to go to the system to request a piece of memory to implement the dynamic array with dynamic memory allocation.

Two, dynamic memory allocation function 1, malloc () function

void *malloc(unsigned int size)

Allocates a size byte of memory space, returns a pointer to the address, and returns null if the memory is not well-divided. Note: The returned pointer is not of type, so it is used to force type conversion.

2. Calloc () function

void *calloc(unsigned int num, unsigned int size)

This is also the application of dynamic memory space, but it is separated. Apply a total of num bytes of memory space length to size byte.

3. Free () function

void free(void *p)

Releases the pointer p memory space.

This is very important!!! Very IMPORTANT!!! Important!!! 4. ReAlloc () function

void *realloc(void *p, unsigned int size)

The storage space requested for the pointer P is changed to size bytes, and the first address of the storage space (pointer) is returned.

Three, dynamic array implementation 1, one-dimensional dynamic array implementation

Dynamicarrayonedimensional.c

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#include <stdio.h>#include <stdlib.h>/**************************************************Dynamicarrayonedimensional.cEnter n number, averaging**************************************************/Main(){ Int*P=Null,N,I,Sum; Printf("Please enter array size:"); scanf("%d",&N); /* Request address n a contiguous storage space of sizeof (int) */ P=(Int*)Malloc(N*sizeof(Int)); If(P==Null) { Printf("No enough memory!\ n"); Exit(0); } Printf("Please enter the score:"); For(I=0;I<N;I++) { scanf("%d",P+I); } Sum=0; For(I=0;I<Ni++) { span class= "n" >sum = sum + * (p + i) } printf ( " aver =%d\n " sum/ n); free (p } /span>

2, two-dimensional dynamic array implementation

Dynamicarraytwodimensional.c

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#include <stdio.h>#include <stdlib.h>IntFindmax(Int*P,IntM,IntN,Int*PRow,Int*Pcol);IntMain(){ Int*Pscore=Null,I,J,M,N,Maxsocre,Row,Col; Printf("Please enter array size m,n:"); scanf("%d,%d",&M,&N); Pscore=(Int*)Calloc(M*N,sizeof(Int)); If(Pscore==Null) { Printf("No enough memory!\ n"); Exit(0); } Printf("Please enter the score:\ n"); For(I=0;I<M;I++) { For(J=0;J<N;J++) { scanf("%d",&Pscore[I*N+J]); } } Maxsocre=Findmax(Pscore,M,N,&Row,&Col); Printf("Maxsocre =%d, class =%d, Number =%d\ n",Maxsocre,Row+1,Col+1); Free(Pscore); Return0;}IntFindmax(Int*P,IntM,IntN,Int*PRow,Int*Pcol){ IntI,J,Max; Max=P[0]; *PRow=0; *Pcol=0; For(I=0;I<M;I++) { For(J=0;J<N;J++) { If(P[I*N+J]>Max) { max = span class= "n" >p[i*n+ j *prow = i;< Span class= "line" > *pcol = j;}} } return (max

C language Dynamic array implementation