我用C编写了一些简单的代码。问题是元素值在循环过程中发生了变化,即使没有这样的命令。循环结束后,第一个循环中计算的所有元素都变为零。但是在第二个或更高编号的循环中计算的元素显示正确的值,它们不会变为零(显然)。那么为什么这些元素变成零?错误在哪里?在c语言循环中数组元素的值自身发生变化
我每次都打印了u(1,0)
的值。
#include <stdio.h> /* Standard Library of Input and Output */
#include <complex.h> /* Standard Library of Complex Numbers */
#include <math.h>
#include <string.h>
#include <stdlib.h>
#define pi 3.141592
int main() {
// Declaration variables
// Integers
int N = 2, Nx = N, Ny = N, i, j; // IMPORTANT GIVE N-1 FOR N
double x[Nx], y[Ny], lengthX = 1.0, lengthY = 1.0;
double complex u[Nx][Ny];
// FOR X DIRECTION
for (i = 0; i <= Nx; i++) {
x[i] = (double)i/(Nx + 1) * lengthX;
//printf("x coordi is %.15f \n", x[i]);
}
// FOR Y DIRECTION
for (j = 0; j <= Ny; j++) {
y[j] = (double)j/(Ny + 1) * lengthY;
//printf("x coordi is %.15f \n", x[i]);
}
for (j = 0; j <= Ny; j++) {
for (i = 0; i <= Nx; i++) {
printf("x coordi is %.15f \n", x[i]);
u[i][j] = sin(2.0 * pi * x[i]) * cos(2.0 * pi * y[j]);
// x[i] = (double)i/(Nx + 1) * lengthX;
printf("u is (i,j) = (%i,%i)\t%.15f\t%f\t%f\n", i, j, u[i][j], x[i], y[j]); //correct
printf("u is (i,j) = (%i,%i)\t element u[1][0] is %.15f \n\n\n", i, j, u[1][0]);
}
printf("\n\n\n End of inside loop (i,j)=(%i,%i) u(1,0) is \t%.15f \n", i, j, u[1][0]);
}
printf("\n\n u is %i\t%i\t%.15f \n\n", i, j, u[1][0]);
printf("\n\n\n\n Why u(1,0) value become zero in the last loop ???????\n");
printf("\n\n\n\n Not only u(1,0) value become zero, but all u(:,0) in the last loop became zero !\n");
//
return 0;
}
'I = 0; i <=Nx' =>'i = 0;如果(j = 0; j <= Ny; j ++)'错误,只能将数组索引到'Ny-1'。否则你的索引不在你的数组中或写在下一行 –
。 –
许多感谢Jean-FrançoisFabre和天气风向标 – STRANGE