字符串中的malloc更换字符 [英] Replacing characters in strings malloc

问题描述

给定一个字符串，两个字符，我想找到的第一个字符多少次存在于字符串，它第一次出现在什么位置，并创建一个新的字符串，其中第二个字符替换每次显示时间第一，但我在与最后一部分的问题。这是我到目前为止有：

Given a string and two characters, I want to find how many times the first character exists on the string, in what position it appears first and create a new string where the second character replaces the first every time it shows up, but I'm having problems with the last part. This is what I have so far:

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

main ()
{
    char string[10], string1;
    char c1, c2;
    int contador, i, l, n, contador2;

    printf ("Introduza uma string e dois caracteres.\n");
    scanf ("%s %c %c", string, &c1, &c2);

    l = strlen (string);
    contador = 0;

    for (n = 0; n < l; n++)
    {
        if (c1 == string[n])
        {
            contador = contador + 1;
        }
    }
    for (n = 0; n < l; n++)
    { 
        if (c1 == string[n])
        {
            contador2 = n + 1; /*Dá-se o valor de n + 1 à variável contador2 porque n começa em 0*/
            break;
        }
    }

    string1 = (char) malloc ((l +1)*sizeof(char));

    for (n = 0; n < l; n++)
    {
        if (c1 == string1[n])
        {
            n = c2;
        }
    }
    printf ("%d\n", contador);
    printf ("%d\n", contador2);
    printf ("%s", string1);
}

我想AP preciate你关心提供任何帮助。

I'd appreciate any help you'd care to offer.

推荐答案

您字符串1 的声明是错误的。它不应该是一个字符而是一个指向字符，的char * 。然后，你也不会动心投的返回值的malloc 。

Your declaration of string1 is wrong. It shouldn't be a char but a pointer to char, char*. Then you also wouldn't be tempted to cast the return value of malloc.

一些小提示：

• 请不要在一个行，如果它们的类型是不同的声明几个变量，尤其如此。


• 将定义的sizeof（char）的是 1 和的malloc 计算它的字符数分配的大小。


• 缩进你的code正确。它不仅使别人更易读，你也将AP preciate它自己，如果你以后再次访问您的code。

• Don't declare several variables in one line, in particular if their types are different.
• By definition sizeof(char) is 1 and malloc counts the size it allocates in the number of char.
• Indent your code properly. Not only it makes it more readable for others, also you will appreciate it yourself if you revisit your code later.

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