How can I read an input string of unknown length?

Question

If I don\'t know how long the word is, I cannot write char m[6];,
The length of the word is maybe ten or twenty long. How can I use scanf to ge

Answer 1

Enter while securing an area dynamically

E.G.

#include 
#include 

char *inputString(FILE* fp, size_t size){
//The size is extended by the input with the value of the provisional
    char *str;
    int ch;
    size_t len = 0;
    str = realloc(NULL, sizeof(char)*size);//size is start size
    if(!str)return str;
    while(EOF!=(ch=fgetc(fp)) && ch != '\n'){
        str[len++]=ch;
        if(len==size){
            str = realloc(str, sizeof(char)*(size+=16));
            if(!str)return str;
        }
    }
    str[len++]='\0';

    return realloc(str, sizeof(char)*len);
}

int main(void){
    char *m;

    printf("input string : ");
    m = inputString(stdin, 10);
    printf("%s\n", m);

    free(m);
    return 0;
}