Исправить ошибки 'for' loop initial declarations are only allowed in C99 mode - C (СИ)

#include <stdio.h>
#include <conio.h>
#include <math.h>
 
#define N 10
#define M 5
 
int main(int argc, char* argv[])
{
    float x[N] = {0} ;
    for (int t1 == 0; t1 < N; t1++)
    {
        printf("x[%d] = ",t1); scanf("%f",&x[t1]);
    }
 
    printf("\n");
 
    float a[M] = { 0 };
    for (int t2 = 0; t2 < M; t2++)
    {
        printf("a[%d] = ",t2); scanf("%f",&a[t2]);
    }
 
    printf("\n");
 
    for (int i = 0; i < M; i++)
        for (int j = 0; j < N; j++)
            if ((x[j] + abs(a[i])) == 15)
                printf("a = %lf x = %lf f(x)=%lf\n",a[i],x[j],pow(x[j],2));
            else if ((x[j] + abs(a[i])) < 15)
                printf("a = %lf x = %lf f(x)=%lf\n",a[i],x[j],a[i] * 2);
            else printf("a = %lf x = %lf f(x)=%lf\n",a[i],x[j],sqrt(a[i]));
 
    _getch();
}