数组二

字符串与字符数组

 

#include <stdio.h>
#include <string.h>//包含strlen函数

int main(void)
{
    printf("size of \"cppcourse\" = %d\n", sizeof("cppcourse"));
    printf("length of \"cppcourse\" = %d\n", strlen("cppcourse"));
    return 0;
}

字符串变量初始化

 

二维数组

 

二维数组初始化

 

 

 

 

对于一维数组，如果下标越界了，得到的值是不确定的，那对于二维数组呢？

 

 

下面以两个实例来操练一下二维数组：

矩阵转置【也就是行变为列，列变为行】

#include <stdio.h>

#define MAX_ROW 2
#define MAX_COL 3

int main(void) 
{
    int i,j;
    int a[MAX_ROW][MAX_COL] = {{1,2,3},{4,5,6}};
    int b[MAX_COL][MAX_ROW];
    printf("Source:\n");
    for(i = 0;i < MAX_ROW;i++)
    {
        for(j = 0;j < MAX_COL;j++)
        {
            printf("%4d",a[i][j]);
        }
        putchar('\n');
    }
    for(i = 0;i < MAX_ROW;i++)
    {    
        for(j = 0;j < MAX_COL;j++)
        {    
            b[j][i] = a[i][j];
        }
    }
    printf("Result:\n");
    for(i = 0;i < MAX_COL;i++)
    {    for(j = 0;j < MAX_ROW;j++)
        {    
            printf("%4d",b[i][j]);
        }
        putchar('\n');
    }
    return 0;
}

运行结果：

 

统计C程序关键字个数

#include <stdio.h>
#include <ctype.h>
#include <string.h>

#define IN    1
#define OUT    0

//二维字符数组来存放C语言中的所有关键字
char keywords[32][9] = {
    "auto",     "break",    "case",     "char",
    "const",    "continue", "default",  "do",
    "double",   "else",     "enum",     "extern",
    "float",    "for",      "goto",     "if",
    "int",      "long",     "register", "return",
    "short",    "signed",   "sizeof",   "static",
    "struct",   "switch",   "typedef",  "union",
    "unsigned", "void",     "volatile", "while"
};

int main(void)
{
    int i, c, state, pos = 0;
    state = OUT;
    char word[32];//这个是用来存放当前解析的关健字，会不断初始化
    int counter[32] = {0};//此变量用来存放关键字出现的次数
    while ((c = getchar()) != EOF)
    {
        if (c == ' ' || c == '\n' || c=='\t')
        {
            state = OUT;
            word[pos] = '\0';
            pos = 0;
            for (i=0; i<32; i++)
            {
                if (strcmp(word, keywords[i]) == 0)
                {
                    counter[i]++;
                    break;
                }
            }
            
        }
        else if (state == OUT)
        {
            state = IN;
            word[pos++] = c;    
        }
        else
            word[pos++] = c;
    }

    for (i=0; i<32; i++)
    {
        printf("%-8s:%d\n", keywords[i], counter[i]);
    }

    return 0;
}

对于空白字符，其实可以用库函数:

#include <stdio.h>
#include <ctype.h>//isspace函数
#include <string.h>

#define IN    1
#define OUT    0

//二维字符数组来存放C语言中的所有关键字
char keywords[32][9] = {
    "auto",     "break",    "case",     "char",
    "const",    "continue", "default",  "do",
    "double",   "else",     "enum",     "extern",
    "float",    "for",      "goto",     "if",
    "int",      "long",     "register", "return",
    "short",    "signed",   "sizeof",   "static",
    "struct",   "switch",   "typedef",  "union",
    "unsigned", "void",     "volatile", "while"
};

int main(void)
{
    int i, c, state, pos = 0;
    state = OUT;
    char word[32];//这个是用来存放当前解析的关健字，会不断初始化
    int counter[32] = {0};//此变量用来存放关键字出现的次数
    while ((c = getchar()) != EOF)
    {
        if (isspace(c))//判断一个字符是否是空白字符可以用isspace库函数，需包含ctype.h头
        {
            state = OUT;
            word[pos] = '\0';
            pos = 0;
            for (i=0; i<32; i++)
            {
                if (strcmp(word, keywords[i]) == 0)
                {
                    counter[i]++;
                    break;
                }
            }
            
        }
        else if (state == OUT)
        {
            state = IN;
            word[pos++] = c;    
        }
        else
            word[pos++] = c;
    }

    for (i=0; i<32; i++)
    {
        printf("%-8s:%d\n", keywords[i], counter[i]);
    }

    return 0;
}

好了，关于数组就学到这，下个内容再见！！