Display operating device and image forming apparatus

A display operating device comprising:

• a software keyboard or a physical keyboard to which a character is to be input by a user;
• a storage that stores therein a plurality of character strings;
• a receiving section configured to receive input of a first character through the software keyboard or the physical keyboard, the receiving section being implemented by a processor that executes a computer program;
• a display that has a display surface and that is configured to display an input frame for display;
• a touch panel configured to detect a touch by a detection target to the display surface of the display, the detection target being a finger or a stylus;
• and
• an extraction section configured to extract one or more first character strings that each are a character string including the first character from among the plurality of character strings, the extraction section being implemented by the processor, wherein
• upon the receiving section receiving input of the first character, the display displays the first character within the input frame and the one or more first character strings extracted by the extraction section outside the input frame,
• in response to detection of a touch operation by the detection target to the first character, the display changes shape, color, or size of the displayed first character,
• the touch operation is sliding of the detection target on the display surface of the display, and is a movement of the detection target in contact with the display surface that moves while changing a movement direction,
• upon the detection section detecting a touch by the detection target to the input frame displaying the first character, the receiving section receives input of a second character through the software keyboard or the physical keyboard,
• the extraction section extracts one or more second character strings that each are a first character string including the second character from among the one or more first character strings, and
• upon the receiving section receiving input of the second character, the display displays the second character within the input frame so that the second character is superposed on the first character having been changed in shape, color, or size, and displays the one or more second character strings extracted by the extraction section outside the input frame.