指针字符串的第一个字符未打印

Question

I'm trying to allocate a dynamic memory for string which is of unknown length (im trying for a mock-compi question) but when i do that my printf wont print the first character from second execution. I'm using gcc 5.something. I've attached a screen shot of the output.

   #include<stdio.h>
   #include<stdlib.h>
   #include<string.h>
   void main (){


    //VARIABELS

        //Input bitstream as a string
        char *stringInput;

        //No of inputs
        int dataCount;

        //memory size to allocate to array
        int dataSize; 

        //FILE pointer
        FILE *fptr;

        //Loop count
        int i;

        //Binary declarations
        long num, decimal_num, remainder, base = 1, binary = 0, noOf1 = 0;



        //MEMORY ALLOCATION

        //Enter N
        printf("Enter N (the number of inputs):\n");
        scanf("%d",&dataCount);

        //+1 for comma (,) characters
        dataSize = ((sizeof(int)+1)* dataCount);

        //Initialize pointer allocated memory
        stringInput = malloc(dataSize);

        if (!stringInput)
        { 
            perror("Error allocating memory");
            abort();
        }

        memset(stringInput, 0, dataSize);
        //Scan the numbers + TEST
        scanf("%s",stringInput);

        //Initialize file pointer
        fptr = fopen("inputString.txt","w"); 
        fprintf(fptr,"%s",stringInput);

        free(stringInput);



        //DECIMAL CONVERSION
        while (num > 0){
            remainder = num % 2;

            //Calc no of 1's
            if (remainder == 1)
                noOf1++;

            //Conversion
            binary = binary + remainder * base;
            num = num / 2;
            base = base * 10;
        }



    }

Answer 1

Change this:

dataSize = ((sizeof(int)+1)* dataCount);

to this:

dataSize = ((sizeof(char) + 1) * (dataCount + 1));

since you want to store a string, not a number.

Notice the +1 I used at the end, which is for the string NULL-terminator.

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PS: What should main() return in C and C++? int .