How to create dynamic array in C?

Question

printf ("%s %d %f\n", (*ptr+i).a, (*ptr+i).b, (*ptr+i).c);
[Error] invalid operands to binary + (have 'struct name' and 'int')

where ptr is a pointer to the structure and allocated dynamic memory using malloc. Any suggestion would be helpful.

Thanks in advance.

Answer 1

Creating 1-D array:---- int type

int n=getSize();
int *arr=( int * ) malloc ( sizeof ( int )  *  n);
//Do Some Stuff :)
..............................
//reallocating the same array.... making the size change:-
m=getSize();     //Getting the new size
arr=(int *) realloc(arr,m);   //You can assign it to any pointer to an integer variable

2-D array:-With Number of rows and number of columns unknown

int n= getRows();
int m=getColumns();
int **arr=NULL;
arr=(int **)malloc(sizeof(int *) * n);
for ( int i=0;i<n;i++){
   arr[i]=(int *) malloc(sizeof(int) * m);

2-D With Number of Columns Unknown but number of rows known say 10:
This can give you variable number of columns

int *arr[10];
for(int i=0;i<10;i++){
    m=getColumns();
    arr[i]=(int *)malloc(sizeof(int) * m);
}

Try for number of rows Unknown urself :) An exercise :) Use pointer to an array.