c - 使用未初始化的局部变量

Question

我的代码出现以下错误:

error C4700: uninitialized local variable 'str_day' used

我正在 Visual Studio Express 2012 中进行编译

这是我的代码:

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

void separate (char *join, char *tempmonth, int *tempday){
    //function to separate month and day from a string
    char *p ;
    p = strtok(join," ");
    strcpy(tempmonth,p);                    // Write the month in tempmonth 
    p = strtok(NULL," ");
    *tempday = atoi(p);                     // Write the day to tempday
}   

int main(){
    char month[20],tempmonth[20],join[30];
    char *str_day;
    int day,tempday;
    printf("Enter the month: ");
    scanf("%s",month);
    printf("Enter the day: ");
    scanf("%d",&day);
    strcpy(join,month);                         
    strcat(join," ");                               //add the month and day seperating by space
    sprintf(str_day,"%d",day);                      //convert day to string to concatenate with month
    strcat(join,str_day);
    separate(join,tempmonth,&tempday);              //call to function separate 
    printf("Month: %s, Day: %d\n",tempmonth,tempday);

    return 0;
}

谁能帮我找出问题所在吗？

Answer 1

替换

char *str_day;

与

char *str_day = malloc(n * sizeof(char)); 

其中 n 是您想要的字符数。 str_day 必须在某处显示(换句话说，被初始化)才能使用它。否则，使用字符数组，例如

char str_day[n]; 

其中 n 是您想要的字符数。