>>289
fscanf を使えってことかな？

#define BUF_SIZE 256
と
char strbuf[BUF_SIZE] = {0};
を消し、

float temp
を
float temp1, temp2
にして、

while (...) {
...
}
を
while (fscanf(fp, "%d %f %f", &day, &temp1, &temp2) != EOF) {
if (min_temp >= temp1) {
min_temp_day = day;
min_temp = temp1;
}
if (max_temp <= temp2) {
max_temp_day = day;
max_temp = temp2;
}
}
にする