c - 由于 C 中的这些指针和数组，程序崩溃

Question

由于这些指针变量，我的代码崩溃了。他们怎么了？

main 中的变量声明

char* fname = (first_name_length*sizeof(char));

char* lname = (last_name_length*sizeof(char));

char* pfname = &fname[0];

char* plname = &lname[0];

功能

void get_first_name(FILE* fp, int length, char* pfname){

char c;
int i = 0;
int number_of_conversions;

//char* first_name = malloc(length*sizeof(char));

number_of_conversions = fscanf(fp, "%c", &c);

while (!isspace(c)){

    pfname[i] = c;

    number_of_conversions = fscanf(fp, "%c", &c);

}

}

Answer 1

char* fname = (first_name_length*sizeof(char));
char* lname = (last_name_length*sizeof(char));

这不是在 C 中分配内存的方式。您可以静态分配内存:

char fname[first_name_length]; //This assumes that first_ and last_name_length are
char lname[last_name_length];  //constants

或者像这样动态地:

char* fname = malloc(first_name_length*sizeof(char)); //first_ and last_name_length can
char* lname = malloc(last_name_length*sizeof(char));  //be constants or variables