二维数组和指针

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代表二维数组的首地址，第0行的地址

n

a+i

代表第i行的地址

–

n

*(a+i) 即 a[i]

代表第i行第0列的地址

–

n

*(a+i)+j 即 a[i]+j

代表第i行第j列的地址

–

n

*(*(a+i)+j ) 即 a[i][j]

代表第i行第j列的元素

–

n

元素a[i][j]的地址的几种等价的引用方式

&a[i][j] – a[i]+j

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*(a+i)+j

– &(*(a+i))[j]

–

n

元素a[i][j]的几种等价的引用方式

a[i][j] – *(a[i]+j) – *(*(a+i)+j)

– –

(*(a+i))[j]

n 二维数组的指针——列指针

int *p;

p = *a;//用列地址初始化

n 相对于数组起始地址的偏移量

– i*m+j

for (i=0; i\"%d\",*(p+i*m+j));

n 二维数组的指针——行指针

int (*p)[3];

p = a;//用行地址初始化

for (i=0; i\"%d\",*(*(p+i)+j));

//指针数组 main() {

int i;

char

*ptr[]

{\"Pascal\ \"Java\ char **p; p = ptr;

for (i=0; i<5; i++) {

printf(\"%s\\n\ p++;

=

} }

动态分配内存

n

在和中均定义了下面的函数 void*

malloc(unsignedint size);

向系统申请大小为size的内存块，把首地址返回。如果申请不成功，返回NULL

n

–

n

void *calloc(unsigned int num, unsigned int size);

–

向系统申请num个size大小的内存块，把首地址返回。如果申请不成功，返回NULL

n

void free(void* p);

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释放由malloc()和calloc()申请的内存块。p是指向此块的指针

一维动态数组 :

#include main() {

int *p = NULL, n, i, sum;

printf(\"Please enter array size:\"); scanf(\"%d\

p = (int *) malloc(n * sizeof (int)); if (p == NULL) {

printf(\"No enough memory!\\n\"); exit(0);

}

printf(\"Please enter the score:\"); for (i=0; iscanf(\"%d\ }

sum = 0;

for (i=0; isum = sum + *(p + i); }

printf(\"aver = %d\\n\ free(p); }

二维动态数组

#include main() {

int *pScore = NULL, i, j, m, n, maxScore, row, col;

printf(\"Please enter array size m,n:\");

scanf(\"%d,%d\

pScore = (int *) calloc(m*n, sizeof (int)); if (p == NULL) {

printf(\"No enough memory!\\n\"); exit(0); }

printf(\"Please enter the score:\"); for (i=0; ifor (j = 0; jscanf(\"%d\ } }

maxScore = FindMax(pScore, 3, 4, &row, &col);

printf(\"maxScore = %d, class = %d, number = %d\\n\

maxScore, row+1, col+1); free(pScore);

}