c - 2D array memory allocation and passing to a function -
i writing program print square,cube,multiples of 4, multiples of 5 2 dimensional array. getting segmentation fault error. can please explain going on? program not print elements of 2d array. ends in segmentation fault after 4th or 6th row.
#include<stdio.h> #include<stdlib.h> void numbers(int ***arr,int nrows,int ncols); void square(int ***arr,int nrows,int ncols); void cube(int ***arr,int nrows,int ncols); void multiples_of_4(int ***arr,int nrows,int ncols); void multiples_of_5(int ***arr,int nrows,int ncols); void free_our_ptr(int ***arr,int nrows,int ncols); int main(void) { int i=0; int nrows = 0; int ncols = 0; int menu_choice = 0; int **arr; printf("\nget number of rows : "); scanf("%d",&nrows); if(nrows > 10) { printf("\nrows should less 10 "); exit(0); } printf("\nget number of columns : "); scanf("%d",&ncols); if(ncols > 10) { printf("\ncolumns should less 10 "); exit(0); } /******* dynamic memory allocation array ***********/ arr = (int **) malloc ( nrows * sizeof(int)); for(i=0;i<nrows;i++) { arr[i] = (int *) malloc ( ncols * sizeof(int)); } /********************************************************/ printf("\nthese choices : "); printf("\nfill integers ---------------- 1"); printf("\nfill squares ---------------- 2"); printf("\nfill cubes ------------------- 3"); printf("\nfill multiples of 4 ---------- 4"); printf("\nfill multiples of 5 ---------- 5"); printf("\n\nenter choice : "); scanf("%d",&menu_choice); switch(menu_choice) { case 1: numbers(&arr,nrows,ncols); break; case 2: square(&arr,nrows,ncols); break; case 3: cube(&arr,nrows,ncols); break; case 4: multiples_of_4(&arr,nrows,ncols); break; case 5: multiples_of_5(&arr,nrows,ncols); break; default : printf("\ninvalid choice, exiting program"); free(arr); exit(0); } exit(0); } void numbers(int ***array,int nrows,int ncols) { int i=0; int j=0; int number = 1; int **arr; arr = *array; for(i=0;i<nrows;i++) { printf("\n"); for(j=0;j<ncols;j++) { arr[i][j] = number; printf("%d\t",arr[i][j]); number++; } } free_our_ptr(&arr,nrows,ncols); } void square(int ***array,int nrows,int ncols) { int i=0; int j=0; int number = 1; int **arr; arr = *array; for(i=0;i<nrows;i++) { printf("\n"); for(j=0;j<ncols;j++) { arr[i][j] = number * number; printf("%d\t",arr[i][j]); ++number; } } free_our_ptr(&arr,nrows,ncols); } void cube(int ***array,int nrows,int ncols) { int i=0; int j=0; int number = 1; int **arr; arr = *array; for(i=0;i<nrows;i++) { printf("\n"); for(j=0;j<ncols;j++) { arr[i][j] = number * number * number; printf("%d\t",arr[i][j]); number++; } } free_our_ptr(&arr,nrows,ncols); } void multiples_of_4(int ***array,int nrows,int ncols) { int i=0; int j=0; int number = 1; int **arr; arr = *array; for(i=0;i<nrows;i++) { printf("\n"); for(j=0;j<ncols;j++) { arr[i][j] = number * 4; printf("%d\t",arr[i][j]); number++; } } free_our_ptr(&arr,nrows,ncols); } void multiples_of_5(int ***array,int nrows,int ncols) { int i=0; int j=0; int number = 1; int **arr; arr = *array; for(i=0;i<nrows;i++) { printf("\n"); for(j=0;j<ncols;j++) { arr[i][j] = number * 5; printf("%d\t",arr[i][j]); number++; } } free_our_ptr(&arr,nrows,ncols); } void free_our_ptr(int ***arr,int nrows,int ncols) { int i; for(i=0;i<nrows;i++) { free(arr[i]); } free(arr); } i tried suggestions, removed free_our_ptr() function altogether , freed memory in main() itself. on ubuntu linux gcc, gives segmentation fault error. however, on visual studio-windows7, runs fine, no errors in test cases. below modified code.
#include<stdlib.h> void numbers(int ***arr,int nrows,int ncols); void square(int ***arr,int nrows,int ncols); void cube(int ***arr,int nrows,int ncols); void multiples_of_4(int ***arr,int nrows,int ncols); void multiples_of_5(int ***arr,int nrows,int ncols); int main(void) { int i=0; int nrows = 0; int ncols = 0; int menu_choice = 0; int **arr; printf("\nget number of rows : "); scanf_s("%d",&nrows); if(nrows > 10) { printf("\nrows should less 10 "); exit(0); } printf("\nget number of columns : "); scanf_s("%d",&ncols); if(ncols > 10) { printf("\ncolumns should less 10 "); exit(0); } printf("\nnumber of rows = %d",nrows); printf("\nnumber of cols = %d",ncols); /******* dynamic memory allocation array ***********/ arr = (int **) malloc ( nrows * sizeof(int)); for(i=0;i<nrows;i++) { arr[i] = (int *) malloc ( ncols * sizeof(int)); } /********************************************************/ printf("\nthese choices : "); printf("\nfill integers ---------------- 1"); printf("\nfill squares ---------------- 2"); printf("\nfill cubes ------------------- 3"); printf("\nfill multiples of 4 ---------- 4"); printf("\nfill multiples of 5 ---------- 5"); printf("\n\nenter choice : "); scanf_s("%d",&menu_choice); switch(menu_choice) { case 1: numbers(&arr,nrows,ncols); break; case 2: square(&arr,nrows,ncols); break; case 3: cube(&arr,nrows,ncols); break; case 4: multiples_of_4(&arr,nrows,ncols); break; case 5: multiples_of_5(&arr,nrows,ncols); break; default : printf("\ninvalid choice, exiting program"); free(arr); exit(0); } free(arr); exit(0); } void numbers(int ***array,int num_rows,int num_columns) { int i=0; int j=0; int number = 1; int **arr; int r1 = num_rows; int c1 = num_columns; arr = *array; printf("\nnumber of rows = %d",r1); printf("\nnumber of cols = %d",c1); for(i=0;i<r1;i++) { printf("\n"); for(j=0;j<c1;j++) { arr[i][j] = number; printf("%d\t",arr[i][j]); number++; } } } void square(int ***array,int num_rows,int num_columns) { int i=0; int j=0; int number = 1; int **arr; int r2 = num_rows; int c2 = num_columns; arr = *array; printf("\nnumber of rows = %d",r2); printf("\nnumber of cols = %d",c2); for(i=0;i<r2;i++) { printf("\n"); for(j=0;j<c2;j++) { arr[i][j] = number * number; printf("%d\t",arr[i][j]); ++number; } } } void cube(int ***array,int num_rows,int num_columns) { int i=0; int j=0; int number = 1; int **arr; int r3 = num_rows; int c3 = num_columns; arr = *array; printf("\nnumber of rows = %d",r3); printf("\nnumber of cols = %d",c3); for(i=0;i<r3;i++) { printf("\n"); for(j=0;j<c3;j++) { arr[i][j] = number * number * number; printf("%d\t",arr[i][j]); number++; } } } void multiples_of_4(int ***array,int num_rows,int num_columns) { int i=0; int j=0; int number = 1; int **arr; int r4 = num_rows; int c4 = num_columns; arr = *array; printf("\nnumber of rows = %d",r4); printf("\nnumber of cols = %d",c4); for(i=0;i<r4;i++) { printf("\n"); for(j=0;j<c4;j++) { arr[i][j] = number * 4; printf("%d\t",arr[i][j]); number++; } } } void multiples_of_5(int ***array,int num_rows,int num_columns) { int i=0; int j=0; int number = 1; int **arr; int r5 = num_rows; int c5 = num_columns; arr = *array; printf("\nnumber of rows = %d",r5); printf("\nnumber of cols = %d",c5); for(i=0;i<r5;i++) { printf("\n"); for(j=0;j<c5;j++) { arr[i][j] = number * 5; printf("%d\t",arr[i][j]); number++; } } }
arr = (int **) malloc ( nrows * sizeof(int)); is not right. needs be
arr = (int **) malloc ( nrows * sizeof(int*)); ^^^^ array of pointers int. the first 1 allocates enough space nrows of ints.
second 1 allocates enough space nrows of int*s.
also, since using c, not c++, don't cast return value of malloc. see do cast result of malloc?
just use:
arr = malloc ( nrows * sizeof(int*)); the function free_our_ptr not right either.
void free_our_ptr(int ***arr,int nrows,int ncols) { int i; for(i=0;i<nrows;i++) { free(arr[i]); ^^^^ not right } free(arr); ^^^ not right. } my suggestion fix change interface to:
void free_our_ptr(int **arr, int nrows, int ncols); ^^^^ use int**, not int***. then, code in function work. however, you'll need change places gets used.
instead of calling as:
free_our_ptr(&arr,nrows,ncols); you'll need call as:
free_our_ptr(arr,nrows,ncols); ^^^ no & 
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