[英]Dynamically allocating a 2D string array
The code seems to be on the right track however it skips out on a row and disregards the first element [0,0] pushing everything completely back by an element. 该代码似乎在正确的轨道上,但是它跳过了一行,而忽略了第一个元素[0,0],将所有内容完全推回了一个元素。
#include <stdio.h>
#include <stdlib.h>
int main()
{
char **nums;
int i,j,k, num_cases;
int rows, cols;
printf("Enter the number of grids.\n");
scanf("%d", &num_cases);
for(k=0;k<num_cases;k++){
printf("Test Case #%d\n", k+1);
printf("Enter the # of rows & columns separated by a space.\n");
scanf("%d%d", &rows, &cols);
nums = (char**)malloc(rows*sizeof(char*));
for(i=0; i<rows; i++){
nums[i] = (char*)malloc(cols*sizeof(char));
}
printf("Enter your %dx%d grid of letters.\n", rows, cols);
for(i=0; i<rows; i++){
for(j=0; j<cols; j++){
scanf("%c", &nums[i][j]);
}
}
}
for(i=0; i<rows; i++){
for(j=0; j<cols; j++){
printf("[%d][%d] = %c\n", i, j, nums[i][j]);
}
}
for(i=0; i<rows; i++){
free(nums[i]);
}
free(nums);
return 0;
}
This line 这条线
scanf("%d%d", &rows, &cols);
is leaving a newline
in the input buffer, because "%d"
format consumes leading whitespace but not trailing whitespace. 在输入缓冲区中保留
newline
,因为"%d"
格式消耗前导空格,但不尾随空格。 So when this line is executed 因此,当执行此行时
scanf("%c", &nums[i][j]);
It reads the newline
that was left. 它读取剩下的
newline
。 You can deal with this by adding a space in front of the "%c"
like this 您可以通过在
"%c"
前面添加一个空格来解决此问题
scanf(" %c", &nums[i][j]);
which will consume any leading whitespace before the char you want to read. 它会在您要读取的char之前占用所有前导空格。
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