动态分配的内存是否需要在周期数不确定的循环中释放？

问：

尝试将字符串缓冲区保留在 C 循环中的未定义行为。

大家好！在引入任何分配方法时，我似乎得到了未定义的行为，尽管我试图遵循我发现的有关释放和解除分配的所有内容。这是一段代码在无限循环中运行，所以我想这可能与它有关？callocmalloc

上下文：尝试在仿真NIOS II处理器的FPGA板上更新数字滤波器的系数。

目前，我已经稍微简化了代码，只是在发送字符后开始将字符收集到中，并在发送字符后停止收集。在这种情况下，可以假设在 和 之间发送的字符不超过 30 个字符，该字符由经过测试的 python 脚本在主机端处理。buffercxcx

} else if (prompt == 'c') {  // check that control signal = c

    // let host know that 'c' is received
    printf("BOARD: preparing for coefficient update\n");
    
    // MEMORY ALLOCATION
    char *buffer = calloc(30, sizeof(char));
    buffer[30] = '\0'; // set a null pointer at the end of string
    
    // check, this should print a blank character
    printf("buffer init is : %c\n", buffer[0]); 

    int count = 0;

    prompt = getc(fp); // reads from jtag_uart interface (tested and working)

    while (prompt != 'x'){
        buffer[count] = prompt;
        printf("buffer inside loop is : %s\n", buffer);
        printf("BOARD >>  Received: %c\n", prompt);
        prompt = getc(fp);
        count++;
    }

    free(buffer);
    buffer=NULL;

}

“未定义”行为仅与以下方面有关： 有时它会在终端中打印（这就是我希望它做的）：buffer

MESSAGE STREAM:
 ['1', '.', '2', ',', '3', '.', '5', ',']
BOARD: preparing for coefficient update
buffer init is :  // <----------------------------
initiating transmission....
HOST: sending 1

buffer inside loop is : 1

BOARD >>  Received: 1

HOST: sending .

buffer inside loop is : 1.

BOARD >>  Received: .

HOST: sending 2

buffer inside loop is : 1.2

BOARD >>  Received: 2

HOST: sending ,
buffer inside loop is : 1.2,

BOARD >>  Received: ,

HOST: sending 3

buffer inside loop is : 1.2,3

BOARD >>  Received: 3

HOST: sending .

buffer inside loop is : 1.2,3.

BOARD >>  Received: .

HOST: sending 5

buffer inside loop is : 1.2,3.5

BOARD >>  Received: 5

HOST: sending ,
buffer inside loop is : 1.2,3.5,

BOARD >>  Received: ,

end of transmission

有时它不会：

MESSAGE STREAM:
 ['3', '.', '4', '5', ',', '2', '.', '4', '4', ',']
BOARD: preparing for coefficient update

initiating transmission....
HOST: sending 3
BOARD >>  Received: 3
HOST: sending .
BOARD >>  Received: .
HOST: sending 4
BOARD >>  Received: 4
HOST: sending 5
BOARD >>  Received: 5
HOST: sending ,
BOARD >>  Received: ,
HOST: sending 2
BOARD >>  Received: 2
HOST: sending .
BOARD >>  Received: .
HOST: sending 4
BOARD >>  Received: 4
HOST: sending 4
BOARD >>  Received: 4
HOST: sending ,
BOARD >>  Received: ,
end of transmission

我假设这是一个问题，因为我对内存分配的概念很陌生，并且该项目的所有其他功能都运行良好 - 并且在不工作时是可以预测的。c

有没有人能够在这里发现任何明显的问题？或者让我知道我是否应该发布其他内容？任何帮助将不胜感激:)

TLDR：尝试保留每个循环周期中附加的字符缓冲区。

结果是未定义的行为，有时它有效，但更多时候，程序只是跳过了打印语句。