c - c语言如何在动态数组中添加/删除字符串

Question

我有一个定义好的数组示例:

char *arguments[] = {"test-1","test-2","test-3"};

我正在尝试添加命令行给出的参数输入。我尝试了 strcpy 函数并通过数组元素传递它，例如arguments[num+1] = argv[1] 但还是没有成功。

我知道这是一个非常简单的问题，但我不是经验丰富的程序员，我的所有经验都来自高级编程语言(PHP、Perl)。

我在网上找到的最接近的工作样本是 C program to insert an element in an array和 C program to delete an element from an array .但并不是我正在寻找的东西，他们使用的是 intigers 而不是我需要的字符。

我的目标是找到一种在动态数组中添加和删除字符串的方法，该数组可以根据脚本的进程增长和收缩。

感谢大家花时间和精力帮助我。

工作代码示例如下:

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

/* Set as minimum parameters 2 */
#define MIN_REQUIRED 2
#define MAX_CHARACTERS 46

/* Usage Instructions */
int help() {
  printf("Usage: test.c [-s <arg0>]\n");
  printf("\t-s: a string program name <arg0>\n");
  printf("\t-s: a string sample name <arg1>\n");
  return (1);
}

int main(int argc, char *argv[]) {

  if ( argc < MIN_REQUIRED ) {
    printf ("Please follow the instructions: not less than %i argument inputs\n",MIN_REQUIRED);
    return help();
  }
  else if ( argc > MIN_REQUIRED ) {
    printf ("Please follow the instructions: not more than %i argument inputs\n",MIN_REQUIRED);
    return help();
  }
  else {
    int size, realsize;
    char *input = NULL;

    char *arguments[] = {"test-1","test-2","test-3"};

    int num = sizeof(arguments) / sizeof(arguments[0]);

    printf("This is the number of elements before: %i\n",num);

    int i;
    for (i=0; i<num; i++) {
      printf("This is the arguments before: [%i]: %s\n",i,arguments[i]);
    }

    printf("This is the input argument: %s\n",argv[1]);
    printf("This is the array element: %i\n",num+1);

    input = (char *)malloc(MAX_CHARACTERS);
    if (input == NULL) {
      printf("malloc_in failled\n");
      exit(0);
    }

    memset ( input , '\0' , MAX_CHARACTERS);

    int length_before = strlen(input);
    printf("This is the length before: %i\n",length_before);
    strcpy(input , argv[1]);
    int length_after = strlen(input);
    printf("This is the length after: %i\n",length_after);

    //arguments[num+1] = input;

    strcpy(arguments[num+1],input);

    int num_2 = sizeof(arguments) / sizeof(arguments[0]);

    printf("This is the number of elements after: %i\n",num);

    for (i=0; i<num_2; i++) {
      printf("This is the arguments after [%i]: %s\n",i,arguments[i]);
    }

  } // End of else condition

  return 0;
} // Enf of int main ()

Answer 1

1. “我的目标是找到一种在动态数组中添加和删除字符串的方法”:

   char *arguments[] = {...} 是静态分配的，因此不能用作“动态数组”。

2. strcpy(参数[num+1],输入):

   当此数组只有 num 个条目时，您无法访问 arguments[num+1]。

---

建议的修复 - 根据 argc 的值动态分配和初始化 arguments:

char* strings[] = {"test-1","test-2","test-3"};
int i, num = sizeof(strings) / sizeof(*strings);
char** arguments = malloc((num+argc-1)*sizeof(char*));
if (arguments == NULL)
    ; // Exit with a failure

for (i=0; i<num; i++)
{
    arguments[i] = malloc(strlen(strings[i])+1);
    if (arguments[i] == NULL)
        ; // Deallocate what's already been allocated, and exit with a failure
    strcpy(arguments[i],strings[i]);
}

for (i=0; i<argc-1; i++)
{
    arguments[num+i] = malloc(strlen(argv[i+1])+1);
    if (arguments[num+i] == NULL)
        ; // Deallocate what's already been allocated, and exit with a failure
    strcpy(arguments[num+i],argv[i+1]);
}

...

// Deallocate everything before ending the program