#include <stdio.h>
#include <stdlib.h>
main(){
int *ptr,r,c,i,j,min;
printf("Give me the size of rows and columns\n");
scanf("%d%d",&r,&c);
int mini[r];
ptr=(int*)malloc(r*c*sizeof(int));
if(ptr== NULL){
printf("Memory not allocated");
}
else{
for(i=0;i<r;i++){
for(j=0;j<c;j++){
printf("Give me the value ");
scanf("%d",&ptr+(i*c+j));
}
}
for(i=0;i<r;i++){
min=*(ptr+i*c);
for(j=0;j<c;j++){
if (*(ptr+i*c)<min){
min = *(ptr+i*c);
}
mini[i]=min;
}
}
for(i=0;i<r;i++){
printf("%d",mini[i]);
}
free(ptr);
}
}
It gets the row and column (r and c ) values without a problem but it crashes as soon as i get to the point of scaning the allocated memory elements. For example if i set r==3 and c==4 then it gets to asking the 10th element of the 12 and then it crashes saying that filename.exe has stopped working.
From my experience I think this has something to do with the scanf() function. I also tried without the & in the scanf, scanf("%d",ptr +(i*c +j)) but then it crashes as soon as it gets to read the first element.
In another much simpler program I wrote to check it the latter scenario of scanf() does not present any problems and the program runs as it was supposed to.
This is wrong
scanf("%d",&ptr+(i*c+j));
it should be
scanf("%d", &(*(ptr + i*c + j)));
or since, the ptr points to the addres, you should not dereference the pointer and then pass the address, just
scanf("%d", ptr + i*c + j);
in your code you are passing the address of the pointer ptr incremented by i * c + j, which is presumably an invalid address, and hence the segmentation fault occur.
Also, it's not the first time I see a scanf() where the return value is ignored, if you type a string then a crash will occur.
You should ensure that an integer was read with
if (scanf("%d", &(*(ptr + i * c + j))) == 1)
if the condition is false, then no value was read, for example if you type text instead of numbers.