打印变量时遇到一些问题。这是我的代码：
int main(int argc, char *argv[]){
int N = 10, i = 0, n = 10;
double v[2] = {0.0,0.0};
double meanS2 = 0.0, sum = 0.0;
time_t t;
srand((unsigned) time(&t));
for(i=0;i<n;i++){
RW(N, v);
meanS2 += v[0]*v[1];
sum += v[1];
}
meanS2 = meanS2/sum;
printf("%f\n", meanS2);
fflush(stdout);
return(0);
}
RW是一个有效的功能（我独立尝试过）。当我运行程序时它什么也没给我。但真的没什么！正如你所看到的，我试图把fflush功能放进去，但它仍然没有给我任何东西。从我所看到的，当程序中存在无限循环时，printf的问题通常会出现，但我的循环远非无限！我真的不明白。我试着把：
RW(N, v);
meanS2 += v[0]*v[1];
sum += v[1];
连续十次，但它没有给我任何东西，实际上当我把它放两次时它起作用，但是三次停止工作。这是否意味着我的RW功能溢出了内存或什么？我是初学者，所以我现在真的迷失了。如果有这样的问题，会不会有消息或什么？
感谢您提供的任何帮助！
这是程序的其余部分以防万一，它应该是一个模拟随机游走与生存偏差：
#define XY(x,y) ((x)*(2*N+1) + (y))
double product(int a, int b) // This function calculate the "scalar product" of two "vectors";
{ // a and b are the vectors giving the directions taken by the walk
double res=0; // +1 and -1 represent going up and down respectively and
// +2 and -2 represent going right and left respectively
if(a == b) // if both of the vectors point in the same direction, the product is 1
{ // since the vectors are of length 1
res = 1.0; // if they point in opposite directions, the result is -1 and
} // if they point in different direction, the result is 0
else if(a == -b)
{
res = -1.0;
}
return res;
}
void RW(int N, double *v)
{
int i, j, step, i_diff, j_diff, p, q, nspots, k, r;
int *lattice, *index_i, *index_j;
int xi;
int dir_i[3], dir_j[3], vec_dir[3];
int *vec;
double S2 = 0;
double w;
lattice = malloc((2*N+1)*(2*N+1)*sizeof(int)); // A lattice big enough so that if the walk goes
index_i = malloc((N+1)*sizeof(int)); // always in the same direction, it stops at the
index_j = malloc((N+1)*sizeof(int)); // edge
vec = malloc(N*sizeof(int)); // index_i and index_j keep tracks of the indices of the different spots the walk goes by, vec keeps tracks of the different directions corresponding (up (1), down (-1), right (2), left (-2))
i = N + 1; // start at the center of the lattice
j = N + 1;
step = 0;
srand (time(NULL));
index_i[step] = i;
index_j[step] = j;
lattice[XY(i,j)] = 1; // 1 means that the walk passed here
xi = rand() % 4 + 1; //For the first step, we take a random number between 1,2,3 and 4
step = 1;
switch(xi)
{
case 1:// if 1, the walk goes down
i++;
index_i[step] = i;
index_j[step] = j;
lattice[XY(i,j)] = 1;
vec[step-1] = -1;
break;
case 2:// if 2, the walk goes up
i--;
index_i[step] = i;
index_j[step] = j;
lattice[XY(i,j)] = 1;
vec[step-1] = 1;
break;
case 3:// if 3, the walk goes right
j++;
index_i[step] = i;
index_j[step] = j;
lattice[XY(i,j)] = 1;
vec[step-1] = 2;
break;
case 4:// if 4, the walk goes left
j--;
index_i[step] = i;
index_j[step] = j;
vec[step-1] = -2;
break;
}
for(step = 2; step<N+1; step++)
{
nspots = 0;
i_diff = i - index_i[step-2]; // difference between the indices we are at right now, and those
j_diff = j - index_j[step-2]; // from one step before
if(i_diff != 0){//dir_i and dir_j represent the indices of the available spots in each case, vec_dir the available direction corresponding
dir_i[0] = i + i_diff;
dir_j[0] = j;
vec_dir[0] = -i_diff;
dir_i[1] = i;
dir_j[1] = j - 1;
vec_dir[1] = -2;
dir_i[2] = i;
dir_j[2] = j + 1;
vec_dir[2] = 2;
for(r=0; r<3; r++){
if(lattice[XY(dir_i[r],dir_j[r])] == 0){
dir_i[nspots] = dir_i[r];
dir_j[nspots] = dir_j[r];
vec_dir[nspots] = vec_dir[r];
nspots++;
}
}
if(nspots == 0){// program aborts if there is nowhere to go
v[0] = 0;
exit(0);
}
}
else if(j_diff != 0){
dir_i[0] = i;
dir_j[0] = j + j_diff;
vec_dir[0] = 2*j_diff;
dir_i[1] = i + 1;
dir_j[1] = j;
vec_dir[1] = -1;
dir_i[2] = i - 1;
dir_j[2] = j;
vec_dir[2] = 1;
for(r=0; r<3; r++){
if(lattice[XY(dir_i[r],dir_j[r])] == 0){
dir_i[nspots] = dir_i[r];
dir_j[nspots] = dir_j[r];
vec_dir[nspots] = vec_dir[r];
nspots++;
}
}
if(nspots == 0){
v[0] = 0;
exit(0);
}
}
w = w*nspots/3;
xi = rand() % nspots;//there are only nspots directions to chose from (no going back)
i = dir_i[xi];
j = dir_j[xi];
lattice[XY(i,j)] = 1;
index_i[step] = i;
index_j[step] = j;
vec[step-1] = vec_dir[xi];
}
// if the walk is completed, calculate S2, the total distance squared
for(p=0; p<N; p++)
{
for(q=0; q<N; q++)
{
S2 += product(vec[p],vec[q]);
}
}
free(lattice);
free(index_i);
free(index_j);
free(vec);
v[0] = S2;
v[1] = w;
}