使用printf&scanf的C程序在输入时崩溃

Question

我正在编写以下c代码并收到错误:

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

int main()
{
char *prot;
char addr[20];
FILE *fp;
int i = 0;
int tos,pld;

prot = (char *)malloc(sizeof(char *));
//addr = (char *)malloc(sizeof(char *));

printf("\n enter the protocol for test::");
scanf(" %s",prot);
printf("\n enter the addr::");
scanf(" %s",addr);
printf("\n enter the length of the payload::");
scanf(" %d",pld);
printf("\n enter the tos :: ");
scanf(" %d",tos);

输入值时出现以下错误.有一个分段错误,任何人都可以告诉我为什么会出现这个段错误:

enter the protocol for test::we

enter the addr::qw

enter the length of the payload::12

Segmentation fault

Answer 1

prot = (char *)malloc(sizeof(char *));

应该:

prot = malloc(sizeof(char) * SIZE); // SIZE is the no. of chars you want

另一个问题是:你应该使用&整数scanf()!

随着变化:

printf("\n enter the length of the payload::");
scanf(" %d",&pld);
printf("\n enter the tos :: ");
scanf(" %d",&tos);