Question

编程以获取输入并输出相反的输出：

#define MAX 1000 

int readtext(char[],int); /*used to store text in array and 
returns the size of the line*/
void reverse(char[]); /*used to reverse the text in the line and
returns 0*/

int main(void)
{
    char text[MAX];
    printf("Enter text, press Ctrl+d when done \n"); /*prompt user input*/

    while((redtext(text, sizeof text)>0)) /*loop repeats until text size is >0*/
    {
        reverse(text);
        printf("%s\n\n",text);
    }
    return 0;
}

int readtext(char a[],int len)
{
    int letchar,i;

    for(i=0;i<len-1 && (letchar=getchar())!=EOF && letchar!='\n';i++) /*for loop repeats until end of line*/
        a[i]=letchar;
    if(letchar=='\n') /*checks if letchar is \n.  if true, changes it to null and returns i value*/
        a[i++]=letchar;
    a[i]='\0';
    return i;   
}

void reverse(char a[])
{
    char t;
    int x,y;
    for(y=0;a[y]!='\0';y++) /*loop used to get the last element of the array*/
        --y;
    for(x=0;x<y;x++) /*loop used to reverse the array 'a'*/ 
    {
        t=a[x];
        a[x]=a[y];
        a[y]=t;
        --y;
    }
}

预期输入/输出：

happy birthday
yadhtrib yppah

我收到此错误消息，但不知道这意味着什么：

/tmp/ccA71SDX.o: In function `main':
1-19.c:(.text+0x63): undefined reference to `redtext'
collect2: ld returned 1 exit status

Answer 1

你在函数调用中犯了一个错误（redtext而不是readtext）。但是你可以使用我的解决方案：

#include <stdio.h>
#include <strings.h>

#define MAXSTRLEN 256

void Reverse(char* str);

int main()
{
    printf("Enter string below:\n");
    char str[MAXSTRLEN];

    fgets(str, MAXSTRLEN, stdin);

    Reverse(str);
    printf("Result:\n%s\n", str);

    return 0;
}

void Reverse(char* str)
{
    char tmp;
    int length = strlen(str) - 1;
    int i;

    for(i = 0; i < length / 2; i++)
    {
        tmp = str[i];
        str[i] = str[length - i - 1];
        str[length - i - 1] = tmp;
    }
}

功能'main'中的错误信息

1 个答案: