Question

我试图让for循环继续，以便用户在稀疏矩阵中输入1的位置。但是我无法理解为什么for循环在一个循环后不会继续。这只是我代码的一部分，其余部分没有必要。

int ** getBinarySparseMatrixFromUser()
{

int r, c, i, f, g;
int **p;

printf("Please enter the number of rows:\n");
scanf("%d", &r);


printf("Please enter the number of columns:\n");
scanf("%d", &c);


    p= malloc(r* sizeof(int*));

    for (i=0; i<r; i++)
    {
        p[i]= malloc(c* sizeof(int));
        printf("in Main : *p[%d]= %d\n", i, p[i]);
    }

    for (i=1; i<r; i++)
    {
        printf("Please enter the number of 1's in row %d :\n", i);
            scanf("%d", &f);

            if (f>0)
            {
                    printf("Please enter column location of the 1's in row: %d\n", i);

                for (i=0; i<f; i++)
                {
                    scanf("%d", &g);
                    p[i][g]= 1;
                }
            }
    }



}

按要求发布的修订代码（仍有错误）：

int ** getBinarySparseMatrixFromUser()
{
int r, c, i, j, f, g;
int **p;

printf("Please enter the number of rows:\n");
scanf("%d", &r);


printf("Please enter the number of columns:\n");
scanf("%d", &c);


    p= malloc(r* sizeof(int*));

    for (i=0; i<r; i++)
    {
        p[i]= malloc(c* sizeof(int));
        printf("in Main : *p[%d]= %d\n", i, p[i]);
    }

    for (i=0; i<r; i++)
    {
        printf("Please enter the number of 1's in row %d :\n", i);
            scanf("%d", &f);

            if (f>0)
            {
                    printf("Please enter column location of the 1's in row: %d\n", i);

                for (j=0; j<f; j++)
                {
                    scanf("%d", &g);
                    p[i][g]= 1;
                }
            }
    }



}

}

Answer 1

我想知道问题是否在重用全局变量＆＃34; i＆＃34;在你的代码的这一部分的内部和外部for循环中：

for (i=1; i<r; i++)
    {
        printf("Please enter the number of 1's in row %d :\n", i);
            scanf("%d", &f);

            if (f>0)
            {
                    printf("Please enter column location of the 1's in row: %d\n", i);

                for (i=0; i<f; i++)
                {
                    scanf("%d", &g);
                    p[i][g]= 1;
                }
            }

尝试为此内部循环使用不同的变量。

Answer 2

哦，好悲伤，我现在明白了。您在两个嵌套循环中使用i作为迭代变量。

for (i = 1; i < r; i++) {  // <---- Using i in outer loop
    printf("Please enter the number of 1's in row %d :\n", i);
    scanf("%d", &f);

    if (f>0) {
        printf("Please enter column location of the 1's in row: %d\n", i);
        for (i = 0; i<f; i++) {  // <--- Also using i in inner loop
            scanf("%d", &g);
            p[i][g] = 1;
        }
    }
}

在C中的for循环中输入2D数组中的值

2 个答案: