[英]Why 2d array repeats the results when i print it in C?
Here the code i wrote:这是我写的代码:
#include <stdio.h>
void ReadData_and_Print(int r, int c, double pin[r][c]);
int main(){
int p[0][0];
ReadData_and_Print(0,0,p[0][0]);
}
void ReadData_and_Print(int r, int c, double pin[r][c])
{
int i=0,j=0;
printf("give rows:");
scanf("%d",&r);
printf("give columns");
scanf("%d",&c);
for (i=0;i<r;i++)
{
for (j=0;j<c;j++)
{
printf("give number:");
scanf("%d",&pin[i][j]);
}
}
for (i=0;i<r;i++)
{
for (j=0;j<c;j++)
{
printf("%d ",pin[i][j]);
}
}
The output: output:
give rows2
give columns3
give number1
give number2
give number3
give number4
give number5
give number6
3 4 5 6 3 4 5 6
When i give 1 2 3 4 5 6 the results is 3 4 5 6 3 4 5 6.Ι should expect 1 2 3 4 5 6. I know is very simple question but its bother me.I do not rule out that is lack of my knowledge about arrays and for.I did research but i cant find the solution.当我给出 1 2 3 4 5 6 时,结果是 3 4 5 6 3 4 5 6。我应该期待 1 2 3 4 5 6。我知道这是一个非常简单的问题,但它困扰着我。我不排除缺乏根据我对 arrays 和 for.I 的了解。我进行了研究,但找不到解决方案。 Thanks in advance.
提前致谢。
You created an array with a dimension of 0. This is a constraint violation in the declaration of an array and therefore invokes undefined behavior .您创建了一个维度为 0 的数组。这违反了数组声明中的约束,因此会调用未定义的行为。
You don't need to define the array in main
or pass it to ReadData_and_Print
.您无需在
main
中定义数组或将其传递给ReadData_and_Print
。 Just declare r
and c
as local to ReadData_and_Print
, read their values, then declare the array after that with those values as the size.只需
r
和c
声明为ReadData_and_Print
的本地,读取它们的值,然后使用这些值作为大小声明数组。
int r, c;
printf("give rows:");
scanf("%d",&r);
printf("give columns");
scanf("%d",&c);
int pin[r][c];
...
Welcome to the world of C!欢迎来到 C 的世界!
Allow me to give an answer first:请允许我先给出一个答案:
#include <stdio.h>
#include <stdlib.h>
void ReadData_and_Print(int r, int c, int ** pin){
int i = 0 ,j = 0;
// Get rows and columns
printf("give rows:");
scanf("%d",&r);
printf("give columns");
scanf("%d",&c);
// Initialize the pin array
pin = (int **) malloc(sizeof(int*) * r);
for (i=0; i<r; i++){
pin[i] = (int *)malloc(sizeof(int) * c);
}
// Scan all the number and store them
for (i=0; i<r; i++){
for (j=0; j<c; j++){
printf("give number:");
scanf("%d",&pin[i][j]);
}
}
// Print them all
for (i=0;i<r;i++){
for (j=0;j<c;j++){
printf("%d ",pin[i][j]);
}
}
}
int main(){
int ** p = NULL;
ReadData_and_Print(0, 0, p);
}
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