Reversing Strings In A 2-D Array

#include<iostream>
using namespace std;
void revstr(char [][30],int);
int main()
{
    int m,i;
    char a[15][30];
    cout<<"Enter number of strings: ";
    cin>>m;
    cout<<"\nEnter the strings :\n\n";
    for(i=0;i<=m;++i)
    {
        cin.getline(a[i],30);
    }
    cout<<"\n\nThe strings are:\n\n";
    for(i=0;i<=m;++i)
    {
        cout<<a[i]<<"\n";
    }
    revstr(a,m);
    cout<<"The reversed strings are :\n\n";
    for(i=0;i<=m;++i)
    {
        cout<<a[i]<<"\n";
    }
    return 0;
}
void revstr(char a[][30],int m)
{
    int i,j,k,len;
    char temp;
    for(i=0;i<=m;++i)
    {
        len=strlen(a[i]);
        for(j=0,k=len-1;j<len/2;++j,--k)
        {
            temp=a[i][j];
            a[i][j]=a[i][k];
            a[i][k]=temp;
        }
    }
}